Key Terms in 1 John
Greek Terms
κοινωνία (koinonia) — Fellowship
The central theme of 1 John. Not mere association, but shared participation in the life of God through Christ. Used of both our fellowship with the Father and Son (1:3, 6) and with one another (1:7).
αἷμα (haima) — Blood
Specifically the blood of Jesus Christ (1:7). In John's theology, the blood represents Christ's atoning death — the sacrifice that cleanses from sin. Not a physical substance but the reality of His poured-out life. "The blood of Jesus His Son cleanses us from all sin" (1:7).
ὁμολογέω (homologeō) — To Confess
Literally "to say the same thing." When we confess our sins, we agree with God's assessment of them — we call sin what He calls it, without excuse or minimization. Confession is the condition for forgiveness and cleansing (1:9).
καθαρίζω (katharizō) — To Cleanse
To purify, make clean. Used in 1 John 1:7, 9 in the present tense — continuous cleansing for the one walking in the light. Not a one-time scrubbing but ongoing purification through Christ's blood.
περιπατέω (peripateō) — To Walk
One's whole way of life, daily conduct. Used throughout 1 John to describe the pattern of one's life — either walking in the light (1:7) or walking in darkness (1:6). Not occasional steps but habitual direction.
ἱλασμός (hilasmos) — Propitiation / Atoning Sacrifice
Jesus is the hilasmos for our sins (2:2; 4:10). Refers to the sacrifice that turns away wrath — Christ satisfies God's righteous requirement against sin.
παράκλητος (parakletos) — Advocate
Used in 2:1: "we have an Advocate with the Father, Jesus Christ the righteous." One called alongside to help. Same word Jesus used of the Holy Spirit in John's Gospel.
τέκνα θεοῦ (tekna theou) — Children of God
John's preferred term for believers (3:1-2, 10; 5:2). Emphasizes the new birth — we are born of God, not adopted into the family.
ἀλήθεια (aletheia) — Truth
Used 20+ times in 1 John. Not abstract truth but the reality of God as revealed in Christ. Walking in truth (1:6, 8) means living in alignment with what God has revealed.
φῶς / σκοτία (phos / skotia) — Light / Darkness
Major contrast in 1:5-2:11. Light = God's moral perfection and the life He gives. Darkness = sin, ignorance, and separation from God. You walk in one or the other — there's no middle ground.
ἀγάπη (agape) — Love
The defining mark of the children of God (4:7-21). Not human affection but God's self-giving, sacrificial love. Known supremely in the cross (4:9-10).
γινώσκω (ginosko) — To Know
Used 25+ times. Relational, experiential knowledge — not intellectual assent. "We know that we know Him" (2:3).
μένω (meno) — To Abide / Remain
Used 24 times. Central to John's theology: the believer abides in Christ, in the truth, in love. Marks the difference between profession and possession.
ψεῦδος / ψεύστης (pseudos / pseustes) — Lie / Liar
John draws sharp lines: those who say they have fellowship but walk in darkness lie (1:6). Denying Jesus is the Christ makes one a liar (2:22). Truth-telling is a mark of genuine faith.
ἐντολή (entolē) — Commandment
Used throughout 1 John for God's specific directives, especially the command to love one another. John calls it both "old" (given from the beginning) and "new" (renewed in Christ with a higher standard — "as I have loved you"). Keeping Christ's commandments is the evidence of knowing Him (2:3-4).
μισέω (miseō) — To Hate
The settled attitude of hostility, indifference, or contempt toward another person. In 1 John, hatred of a brother is the definitive proof that one is walking in darkness rather than light (2:9-11). John uses it as the polar opposite of agapaō (to love).
τηρέω (tēreō) — To Keep / Guard
To observe, hold in one's custody, guard carefully. Used of keeping God's commandments (2:3-5) — not perfect, sinless obedience but the general posture of a life that treasures God's Word and aims to obey it. The same word is used of keeping oneself from idols (5:21).
τεκνία (teknia) — Little Children
John's characteristic term of endearment for believers, meaning "little born-ones" (2:1, 12, 28; 3:7; 4:4; 5:21). Emphasizes the new birth — believers are not merely followers of Christ but children of God, born into His family. In 2:12-14, teknia also represents the first stage of spiritual growth, marked by forgiveness and knowing the Father.
νεανίσκοι (neaniskoi) — Young Men
The second stage of spiritual growth in 1 John 2:12-14. Characterized by strength derived from the Word of God abiding in them, and by victory over the wicked one (Satan). The young man represents the believer who has progressed from knowing forgiveness to learning spiritual warfare.
κόσμος (kosmos) — World
Used in two distinct senses in 1 John: (1) the world of people for whom Christ died (2:2; 4:14); (2) the fallen world system organized in opposition to God (2:15-17; 3:1; 5:4-5). In the latter sense, characterized by the lust of the flesh, the lust of the eyes, and the pride of life. The world is passing away; the one who does God's will abides forever.
ἐπιθυμία (epithumia) — Lust / Strong Desire
Used in 2:16-17 of worldly cravings that compete with God for the heart. In itself a neutral word for strong desire, but in 1 John it appears in the phrase epithumia sarkos (lust of the flesh) — desires arising from fallen human nature that seek satisfaction apart from God's will. Contrasted with doing the will of God, which abides forever.
ἀντίχριστος (antichristos) — Antichrist
One who opposes Christ or substitutes a false Christ. Used only in 1 John (2:18, 22; 4:3) and 2 John 7. Refers both to the coming ultimate opponent of Christ (the "antichrist" of 2:18) and the many false teachers already active ("many antichrists" — 2:18). The defining mark of antichrist is denying that Jesus is the Christ, the Son of God come in the flesh (2:22; 4:3).
χρίσμα (chrisma) — Anointing
Used in 2:20 and 2:27 of the Holy Spirit's indwelling work in every believer. From the same root as Christos (the Anointed One). The anointing teaches believers the truth about Christ, abides in them permanently, and makes them able to discern truth from error. John's point: believers do not need the secret knowledge false teachers claim — the Spirit Himself is their Teacher.
παρουσία (parousia) — Coming / Presence
Used in 2:28 of Christ's visible, glorious return. A technical term for the arrival of a king or ruler. The believer who abides in Christ can face His parousia with confidence (parrēsia) rather than shame. The same word appears in the New Testament for Christ's second coming (Matthew 24:3, 27; 1 Thessalonians 4:15; 2 Thessalonians 2:1).
ἁγνίζω (hagnizō) — To Purify, Cleanse
Used in 3:3: "everyone who thus hopes in Him purifies himself as He is pure." The active, ongoing work of a believer who looks forward to Christ's appearing. Purification is not passive — it is a deliberate setting apart of oneself for holy use, motivated by the hope of seeing Christ.
ἁμαρτία (hamartia) — Sin
The most common New Testament word for sin, meaning literally "to miss the mark." In 1 John, sin is defined as lawlessness — a spirit of rebellion against God's authority (3:4). Christ appeared to take away sins (3:5), and everyone born of God does not make a practice of sinning (3:9). John distinguishes between occasional stumbling (confessed and cleansed, 1:8-9) and habitual, unrepentant sinning, which is incompatible with the new birth (3:6, 9).
ἀνομία (anomia) — Lawlessness
John's definition of sin in 3:4: "sin is lawlessness." Not merely breaking rules but living as if there were no law — a spirit of autonomy and rebellion against God's authority. The opposite of righteousness.
δικαιοσύνη (dikaiosynē) — Righteousness
Righteousness in conduct and character; the visible evidence of being born of God (2:29; 3:7, 10). In 1 John, righteousness is not a legal status (imputed righteousness) but a practical way of living (practiced righteousness). The one who is righteous "as He is righteous" (3:7) does what is right because his new nature loves what God loves.
καρδία (kardia) — Heart
The inner person — conscience, thoughts, intentions, emotions. In 3:20-21, John speaks of the heart as a witness that can either condemn or reassure us. The heart is not infallible; God is greater than our heart and knows everything.
καταγινώσκω (kataginoskō) — To Condemn
Used in 3:20-21 of the heart's inner accusation: "if our heart condemns us." The opposite of parrēsia (confidence). The remedy for a condemning heart is not self-improvement but the greater knowledge of God, who sees the whole picture and judges by Christ.
σπέρμα (sperma) — Seed
Used in 3:9: "God's seed abides in him." The divine life implanted in the believer at the new birth — the indwelling Holy Spirit, the new nature, the life of Christ Himself. This seed abides permanently and makes a life of habitual sin impossible for the one born of God.
τίθημι (tithēmi) — To Lay Down
Used in 3:16 of Christ's sacrificial death: "He laid down His life for us." The same word Jesus used in John 10:11, 15, 17-18 of the Good Shepherd laying down His life for the sheep. A voluntary, deliberate, substitutionary act. Sets the pattern for the believer's love: "we ought to lay down our lives for the brothers."
φαινερόω (phaneroō) — To Appear, Manifest, Make Visible
A key word in 1 John used of both Christ's first coming (1:2; 3:5, 8) and His second coming (2:28; 3:2). Christ appeared (was manifested) to bring eternal life, to take away sins, and to destroy the works of the devil. When He appears again, we shall be like Him, for we shall see Him as He is.
φαινερός (phaneros) — Evident, Manifest, Visible
Used in 3:10: "By this it is evident who are the children of God." The distinction between the two families is not hidden — it is visible in the way people live and love.
πείθω (peithō) — To Persuade, Reassure, Set at Rest
Used in 3:19 of calming a troubled conscience: "reassure our heart before Him." The process of bringing inner peace through the truth of God's greater knowledge and grace.
πνεῦμα (pneuma) — Spirit
Used in 3:24 of the Holy Spirit's internal witness: "by this we know that He abides in us, by the Spirit whom He has given us." The Spirit is both the evidence of our union with Christ and the power by which we obey and love. John develops the Spirit's role extensively in chapter 4 (testing the spirits, 4:1-6; the Spirit of truth, 4:6).
δοκιμάζω (dokimazō) — To Test, Examine, Prove
Used in 4:1: "test the spirits." The word means to examine for genuineness, like testing metals to see if they are authentic. Believers are commanded to test every spirit rather than naively accept every spiritual claim. The faith that cannot be tested cannot be trusted.
ψευδοπροφήτης (pseudoprophētēs) — False Prophet
One who speaks falsely in God's name. Used in 4:1: "many false prophets have gone out into the world." Not merely mistaken teachers but deliberately misleading ones who represent Satan's interests while claiming to speak for God.
νικάω (nikaō) — To Overcome, Conquer, Prevail
Used in 4:4 in the perfect tense: "you have overcome them." A past victory with continuing results. The believer's victory over the spirit of antichrist is not future but already accomplished — because the indwelling Christ has already conquered. This same verb appears in 5:4-5 of faith overcoming the world.
μονογενής (monogenēs) — Only Son, Only-Begotten, Unique
Used in 4:9: "God sent his only Son into the world." Emphasizes the uniqueness of Christ's relationship to the Father. There is no other like Him. The Father gave His most precious possession — His one-of-a-kind Son — as the demonstration of His love.
τελειόω (teleioō) — To Perfect, Bring to Completion, Accomplish
Used twice in chapter 4: "his love is perfected in us" (4:12) and "whoever fears has not been perfected in love" (4:18). The word does not mean sinless perfection but "brought to its intended goal." God's love reaches its purpose when it flows through us to others. Fear reveals that love has not yet fully done its work in the heart.
φόβος (phobos) — Fear
Used in 4:18 of the fear of judgment and punishment. In 1 John, this is not the healthy caution that preserves life but the terror of a guilty conscience facing God's wrath. Perfect love casts out this kind of fear because Christ has already taken the punishment. Fear and love are mutually exclusive — where one dwells, the other is expelled.
κόλασις (kolasis) — Punishment
Used in 4:18: "fear has to do with punishment." The penalty or retribution deserved for sin. Fear clings to the anticipation of punishment. Perfect love knows that Christ has already borne the punishment for His people, leaving nothing to fear. The believer does not cringe before a Judge but runs to a Father.
πίστις (pistis) — Faith
Trust, confidence, reliance. Used in 5:4: "this is the victory that has overcome the world — our faith." Faith is not a vague optimism but specific trust in Jesus as the Son of God. It is the instrument of victory — the channel through which Christ's already-won victory flows into the believer's life.
μαρτυρία (martyria) — Testimony, Witness
Evidence, proof, attestation. Used throughout 5:6-12 of the three witnesses God gives concerning His Son: the Spirit, the water, and the blood. These three agree in one, providing an objective foundation for faith. To reject God's testimony is to make Him a liar.
ζωὴ αἰώνιος (zōē aiōnios) — Eternal Life
Not merely unending existence but the life of God Himself — the quality of life that belongs to the age to come, experienced now by those who are in Christ. In 1 John, eternal life is not a reward for good behavior but a Person: "He who has the Son has life" (5:12). Eternal life is knowing the true God through His Son (5:20).
οἶδα (oida) — To Know (With Certainty)
Absolute, settled knowledge. Used three times in 5:18-20 as the foundation of assurance: "We know..." John distinguishes this from mere intellectual knowledge (ginoskō). Oida carries the sense of intuitive, immediate, certain knowledge — the confidence of a child who knows his Father.
διάνοια (dianoia) — Understanding, Comprehension
Spiritual perception, the capacity to apprehend spiritual reality. Used in 5:20: "the Son of God has come and has given us understanding, so that we may know him who is true." This is not natural intelligence but a gift from Christ that enables us to know God.
εἴδωλον (eidōlon) — Idol
Used in 5:21: "keep yourselves from idols." Anything that takes the place of God in the heart — any competing affection, trust, or object of worship. The heart is an idol factory, and the only safeguard is constant vigilance. The letter ends with this practical warning because the knowledge of the true God demands that we guard our hearts against everything that would displace Him.
Key Phrases
"God is light" (1:5)
The foundational announcement of the epistle. Not "God gives light" or "God is like light" — God is light. His nature is absolute moral perfection, truth, and holiness, with no trace of darkness. This is the standard for fellowship: because God is light, His people must walk in the light.
"If we confess our sins" (1:9)
The believer's recovery mechanism. Confession (homologeō = to say the same thing) restores broken fellowship. God forgives and cleanses not because of our merit but because He is faithful to His Son's atoning work and just to those who come through Christ.
"That your joy may be full" (1:4)
John's stated purpose. The word plēroō means filled to completion — not partial joy but full, running-over joy found in fellowship with God.
"We have an Advocate" (2:1)
The believer's confidence: when we sin, Christ is our defense attorney before the Father, not based on our merit but on His righteousness.
"Let us not love in word or talk but in deed and in truth" (3:18)
The simplest and most searching summary of the Christian ethic. John does not condemn words of love entirely, but love that stays in words only is empty. True love must be both practical (in deed) and genuine (in truth). The love that passes from death to life is a love that opens its hands because Christ opened His on the cross.
"Believe in the name of His Son Jesus Christ and love one another" (3:23)
John's distillation of the entire Christian duty into one twofold commandment. Faith (the doctrinal test) and love (the love test) are inseparable — faith is the root, love is the fruit. To "believe in the name" means personal trust in everything Christ's name represents: His person, His work, His authority.
"He who has the Son has life" (5:12)
The great divide: life is not a state but a Person. You either possess Christ (and therefore life) or you don't.
"Everyone who practices righteousness is born of Him" (2:29)
The moral test in its most distilled form. Being born of God produces a new nature, and the new nature expresses itself in righteous living. Righteous conduct is not the cause of the new birth but its evidence. Introduced at the close of chapter 2 as a bridge to the fuller treatment of the new birth in chapter 3.
"Behold what manner of love" (3:1)
An exclamation of wonder at the Father's love that makes sinners into sons. The phrase potapēn agapēn literally asks "what country does this love come from?" — a love from another world, utterly foreign to anything natural to humanity. This love is a gift, not a reward, and its result is that we are called — and are — children of God.
"The Son of God appeared to destroy the works of the devil" (3:8)
The purpose of the incarnation in a single sentence. Christ came not only to save but to destroy — to undo everything sin and Satan have done. The cross was not merely a rescue mission but a conquest. This is the foundation of the believer's victory over sin: the One who is in us is greater than the one who is in the world.
"We know that we have passed from death to life" (3:14)
The assurance of salvation — a present reality, not a future hope. Evidence: love for the brethren.
"Test the spirits" (4:1)
The command to discern whether a teacher or teaching is from God. Not blind suspicion but active, careful testing by three criteria: the Word of God (apostolic Scripture), the Son of God (confession of the incarnation), and the Spirit of God (internal witness and illumination). The faith that cannot be tested cannot be trusted.
"Greater is He who is in you than he who is in the world" (4:4)
The believer's confidence in spiritual warfare. The indwelling Holy Spirit is greater than the spirit of antichrist at work in the world. The victory is not in our cleverness or discernment but in Christ's conquest. We do not fight for victory but from victory.
"God is love" (4:8, 16)
The second great "God is" declaration in 1 John (cf. "God is light," 1:5). Love is not merely an attribute of God but His essential nature. Everything He does is consistent with love. This does not contradict "God is light" — His holiness defines His character, and His love defines His disposition toward His creatures. The two never compete in Him.
"In this is love, not that we have loved God but that He loved us" (4:10)
The most precise definition of love in all of Scripture. Love is defined not by human affection or emotion but by God's historical act of sending His Son as the propitiation for our sins. The initiative is always with God. Our love is always response, never initiation. This verse dismantles every human religion.
"As He is, so are we in this world" (4:17)
The believer's identification with Christ. Not "as He was" but "as He is" — now, exalted at the Father's right hand. What is true of Christ is true of the believer in union with Him: His wisdom, joy, sorrows, friends, enemies, purpose, authority, and future are ours. This is the ground of confidence on the day of judgment.
"Perfect love casts out fear" (4:18)
The incompatibility of mature love and the fear of judgment. Fear clings to the anticipation of punishment. Perfect love knows that Christ has already taken the punishment, leaving nothing to fear. The remedy for fear is not to try harder but to look longer at the cross. Where the cross is fully understood, fear cannot survive.
"We love because He first loved us" (4:19)
The gospel in seven words. Our love is never the cause of God's love but always the response to it. He initiated while we were still sinners. Every ounce of love in our hearts — for God or for others — flows from His prior love. This is both the most humbling and the most liberating truth in the Christian life.
"This is the victory that has overcome the world, even our faith" (5:4)
The victory is not in our strength but in our faith — and faith is only as good as its object. The perfect tense "has overcome" points to a victory already won by Christ. Our faith is the channel through which His victory flows into our lives. The overcomer is not the exceptional Christian but the normal one — everyone born of God overcomes the world.
"He who has the Son has life" (5:12)
The great divide. Eternal life is not a thing God gives but a Person we possess. It is not a duration of existence but a relationship with Christ. You either have the Son (and therefore life) or you do not have the Son (and therefore do not have life). There is no third category. All the tests in this letter converge on this single point.
"That you may know that you have eternal life" (5:13)
John's stated purpose for writing the entire letter. The word "know" (oida) means absolute, settled certainty. God does not want His children to live in doubt. He wants us to know — not hope, guess, or wish — that we have eternal life. The tests, the witnesses, and the "we know" affirmations are all given for this purpose: settled, confident assurance.
"Keep yourselves from idols" (5:21)
The final command of the letter. An idol is anything that takes the place of God in the heart. The verb "keep" (phylassō) means to guard, to watch over, to protect — implying constant vigilance. The letter began with fellowship (1:3) and ends with a warning against everything that would disrupt it. The knowledge of the true God demands that we guard our hearts against every competing affection.