Strong's #571: apistos (pronounced ap'-is-tos)

from 1 (as a negative particle) and 4103; (actively) disbelieving, i.e. without Christian faith (specially, a heathen); (passively) untrustworthy (person), or incredible (thing):--that believeth not, faithless, incredible thing, infidel, unbeliever(-ing).

Thayer's Greek Lexicon:

̓́

apistos

1) unfaithful, faithless, (not to be trusted, perfidious)

2) incredible

2a) of things

3) unbelieving, incredulous

3a) without trust (in God)

Part of Speech: adjective

Relation: from G1 (as a negative particle) and G4103

Citing in TDNT: 6:174, 849

Usage:

This word is used 23 times:

 

Matthew 17:17: "answered and said, O faithless and perverse generation, how long"
Mark 9:19: "him, and saith, O faithless generation, how long shall I be"
Luke 9:41: "answering said, O faithless and perverse generation, how long"
Luke 12:46: "and will appoint him his portion with the unbelievers."
John 20:27: "and be not faithless, but believing."
Acts 26:8: "Why should it be thought a thing incredible with you, that God should raise"
1 Corinthians 6:6: "and that before the unbelievers."
1 Corinthians 7:12: "brother hath a wife that believeth not, and she be pleased to dwell"
1 Corinthians 7:13: "which hath a husband that believeth not, and if he be pleased to dwell"
1 Corinthians 7:14: "For the unbelieving husband is sanctified by the wife,"
1 Corinthians 7:14: "wife, and the unbelieving wife is sanctified by the"
1 Corinthians 7:15: "But if the unbelieving depart, let him depart. A brother or"
1 Corinthians 10:27: "If any of them that believe not bid you to a feast, and ye be disposed"
1 Corinthians 14:22: "not to them that believe, but to them that believe not: but prophesying serveth not for them that believe not,"
1 Corinthians 14:22: "but prophesying serveth not for them that believe not, but for them which believe."
1 Corinthians 14:23: "there come in those that are unlearned, or unbelievers, will they not say that ye are mad?"
1 Corinthians 14:24: "and there come in one that believeth not, or one unlearned, he is convinced of"
2 Corinthians 4:4: "hath blinded the minds of them which believe not, lest the light of the"
2 Corinthians 6:14: "Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness"
2 Corinthians 6:15: "what part hath he that believeth with an infidel?"
1 Timothy 5:8: "faith, and is worse than an infidel."
Titus 1:15: "unto them that are defiled and unbelieving is nothing pure; but even"
Revelation 21:8: "But the fearful, and unbelieving, and abominable, and murderers,"