What is The Definition of Blaspheme?

Blaspheme means to speak against the Lord, or ascribe to the Lord less honor, respect, or reverence than is due unto Him, particularly in the words that you say.
Saying something about God that is not true so you don't have to honor Him as Lord is blasphemy and you would have said to be blaspheming The Lord.
In other words, removing God's honor by the words that you say is blasphemy.

Greek Word Study: βλασφημία (blasphēmía)

Meaning: “Speech that dishonors, insults, or defames,” especially speech directed against God.

Basic Definition

βλασφημία (blasphēmía)
Root idea: verbal injury — damaging speech that attacks the reputation, character, or work of God or people.

Closely related verb: βλασφημέω (blasphēmeō) — “to slander, speak irreverently, revile, mock, insult.”

Etymology

From βλάπτω (blaptō) – to harm
And φήμη (phēmē) – speech, report, utterance

Thus the literal sense:
“harmful speech,” “speech that damages.”

In biblical usage, the harm is moral and spiritual, not merely reputational.

Septuagint (LXX)

Used for Hebrew words meaning:

נָקַב / nāqab – to curse or pierce with words (Leviticus 24:11,16)
חֵרֵף / ḥērēf – to reproach or taunt God (2 Kings 19:6)
גִּדֵּף / giddēf – to blaspheme or revile (Psalm 74:18)

Thus, the NT meaning stands firmly on OT roots: speech that dishonors the Holy One.

βλασφημία refers not merely to harsh language but to intentional degradation of God’s person, works, or Spirit. In fact, the “blasphemy against the Holy Spirit” described by The Lord Jesus focuses on knowingly rejecting the Spirit’s testimony to Christ, not accidental or ignorant speech.

Scriptures That Define Blaspheme

Luke 12:10 - And whosoever shall speak a word against the Son of man, it shall be forgiven him: but unto him that blasphemeth against the Holy Ghost it shall not be forgiven.
Acts 7:51 - Ye stiffnecked and uncircumcised in heart and ears, ye do always resist the Holy Ghost: as your fathers did, so do ye.
Revelation 13:6 - And he opened his mouth in blasphemy against God, to blaspheme his name, and his tabernacle, and them that dwell in heaven.
Revelation 13:1 - And I stood upon the sand of the sea, and saw a beast rise up out of the sea, having seven heads and ten horns, and upon his horns ten crowns, and upon his heads the name of blasphemy.
Mark 2:7 - Why doth this man thus speak blasphemies? Who can forgive sins but God only?
2 Thessalonians 2:4 - Who opposeth and exalteth himself above all that is called God, or that is worshipped; so that he as God sitteth in the temple of God, shewing himself that he is God.

More Scriptures on Blasphemy

Matthew 12:31-32 - Wherefore I say unto you, All manner of sin and blasphemy shall be forgiven unto men: but the blasphemy against the Holy Ghost shall not be forgiven unto men.
Mark 3:29 - But he that shall blaspheme against the Holy Ghost hath never forgiveness, but is in danger of eternal damnation:
Titus 2:3-5 - The aged women likewise, that they be in behaviour as becometh holiness, not false accusers, not given to much wine, teachers of good things; That they may teach the young women to be sober, to love their husbands, to love their children, To be discreet, chaste, keepers at home, good, obedient to their own husbands, that the word of God be not blasphemed.
Hebrews 10:29 - Of how much sorer punishment, suppose ye, shall he be thought worthy, who hath trodden under foot the Son of God, and hath counted the blood of the covenant, wherewith he was sanctified, an unholy thing, and hath done despite unto the Spirit of grace?

Here are Biblical Scholars on This Topic:

Scholars on Blasphemy

Scholar	View on Blasphemy (Scriptural Reference added)
Justin Martyr (c. 100–165)	Justin teaches that blasphemy arises when one knowingly dishonors God’s truth through speech or denial (Matthew 12:31). He sees it as a rebellion of the will, not merely careless words.
Irenaeus of Lyons (c. 130–202)	Irenaeus argues that blasphemy occurs when one contradicts the Spirit’s witness to Christ after receiving clear revelation (Mark 3:29). He emphasizes that such rejection is deliberate and hardened.
Tertullian (c. 155–240)	Tertullian views blasphemy as contempt toward God’s majesty expressed in speech (Leviticus 24:16). He warns that persistent refusal of the Spirit’s testimony is especially grave.
Origen of Alexandria (c. 184–253)	Origen teaches that blasphemy is the misuse of speech against God, arising from a resistant and darkened heart (Matthew 12:31–32). He distinguishes between ignorant error and willful hostility to the Spirit.
Athanasius of Alexandria (c. 296–373)	Athanasius sees blasphemy as denying or degrading God’s nature, particularly the Spirit’s divine work (Mark 3:28–29). He affirms its seriousness because it rejects the light given by God Himself.
Basil the Great (c. 329–379)	Basil holds that blasphemy attacks the honor of the Holy Trinity, especially the Spirit’s divine glory (Matthew 12:31). He insists that this sin stems from deliberate resistance.
John Chrysostom (c. 347–407)	Chrysostom explains that blasphemy is knowingly attributing the works of God to evil (Mark 3:30). Its danger lies in closing the heart to divine mercy.
Jerome (c. 347–420)	Jerome teaches that blasphemy mocks God’s holiness and rejects His testimony (Psalm 74:18). He stresses that the sin against the Spirit involves conscious rejection of known truth.
Augustine of Hippo (354–430)	Augustine defines blasphemy as dishonoring God through speech and willful malice (Matthew 12:31–32). He links the unpardonable form to hardened resistance to grace.
Thomas Aquinas (1225–1274)	Aquinas says blasphemy is “speaking evil of God,” a sin rooted in the intellect and will (Leviticus 24:15). He teaches that the worst form is obstinate refusal of the Spirit’s light.
Bonaventure (1221–1274)	Bonaventure views blasphemy as degrading divine goodness through malicious speech (Psalm 74:22). He emphasizes that its severity increases with knowledge of truth.
John Wycliffe (c. 1330–1384)	Wycliffe teaches that blasphemy contradicts God’s truth and corrupts Christian confession (Mark 3:29). He considers it a sign of deep spiritual rebellion.
Martin Luther (1483–1546)	Luther sees blasphemy as knowingly cursing or denying God’s revealed Word (1 Timothy 1:13). He argues that blasphemy of the Spirit is deliberate, enlightened hostility to the gospel.
John Calvin (1509–1564)	Calvin teaches that blasphemy of the Spirit is a conscious, malicious rejection of the gospel after clear conviction (Mark 3:28–30). It is not ignorance but chosen hatred of divine truth.
Theodore Beza (1519–1605)	Beza defines blasphemy as intentional insult against God’s majesty (Matthew 12:31). He stresses that no sin is unpardonable except final, willful defiance of the Spirit.
Richard Baxter (1615–1691)	Baxter argues that blasphemy springs from contempt for God’s holiness and mercy (Ephesians 4:31). He warns that the greatest danger lies in rejecting the Spirit’s inward witness.
John Owen (1616–1683)	Owen teaches that blasphemy is deliberate defiance against God’s Spirit, especially by resisting His convicting work (Hebrews 10:29). He notes that it reflects hardened enmity.
Jonathan Edwards (1703–1758)	Edwards sees blasphemy as malicious opposition to God expressed in speech or thought (Matthew 12:31–32). He argues that its most severe form arises from clear knowledge joined with hatred.
Charles Hodge (1797–1878)	Hodge teaches that blasphemy is open contempt for God’s name or works (Psalm 74:18). He ties the sin against the Spirit to continued, knowing rejection of gospel truth.
B. B. Warfield (1851–1921)	Warfield argues that blasphemy is moral revolt against God’s character and divine operations (Mark 3:29). He emphasizes that blasphemy of the Spirit is not momentary but a hardened stance.