From pistis; to have faith (in, upon, or with respect to, a person or thing), i.e. Credit; by implication, to entrust (especially one's spiritual well-being to Christ) -- believe(-r), commit (to trust), put in trust with.

see GREEK pistis

1. intransitive, to think to be true; to be persuaded of; to credit, place confidence in;

a. universally: the thing believed being evident from the preceding context, Matthew 24:23,(26); Mark 13:21; 1 Corinthians 11:18; with an accusative of the thing, Acts 13:41 (L T Tr WH ὁ for Rec. ᾧ), to credit, have confidence, followed by ὅτι, Acts 9:26; τίνι, to believe one's words, Mark 16:13; 1 John 4:1; τίνι ὅτι, John 4:21; τῷ ψεύδει, 2 Thessalonians 2:11; περί τίνος, ὅτι, John 9:18.

b. specifically, in a moral and religious reference, πιστεύειν is used in the N. T. of "the conviction and trust to which a man is impelled by a certain inner and higher prerogative and law of his soul"; thus it stands α. absolutely to trust in Jesus or in God as able to aid either in obtaining or in doing something: Matthew 8:13; Matthew 21:22; Mark 5:36; Mark 9:23; Luke 8:50; John 11:40; followed by ὅτι, Matthew 9:28; Mark 11:23; (Hebrews 11:6); τῷ λόγῳ, ᾧ (ὅν) εἶπεν ὁ Ἰησοῦς, John 4:50. β. of the credence given to God's messengers and their words, with a dative of the person or thing: Μωϋσεῖ John 5:46. to the prophets, John 12:38; Acts 24:14; Acts 26:27; Romans 10:16; ἐπί πᾶσιν οἷς ἐλάλησαν οἱ προφῆται, to place reliance on etc. Luke 24:25. to an angel, Luke 1:20; followed by ὅτι, Luke 1:45. to John the Baptist, Matthew 21:25 (26),32; Mark 11:31; Luke 20:5. to Christ's words, John 3:12; John 5:38, 46; John 6:30; John 8:45; John 10:(37),38{a}; τοῖς ἔργοις of Christ, John 10:38{b}. to the teachings of evangelists and apostles, Acts 8:12; τῇ ἀλήθεια, 2 Thessalonians 2:12; ἐπιστεύθη τό μαρτύριον, the testimony was believed, 2 Thessalonians 1:10 (cf. Winers Grammar, § 39,1 a.; Buttmann, 175 (152)); τῇ γραφή, John 2:22. ἐν τῷ εὐαγγελίῳ, to put faith in the gospel, Mark 1:15 (Buttmann, 174 (151f); cf. Winers Grammar, 213 (200f)) (Ignatius ad Philad. 8, 2 [ET] ((but see Zahn's note); cf. John 3:15 in γ. below)). γ. used especially of the faith by which a man embraces Jesus, i. e. "a conviction, full of joyful trust, that Jesus is the Messiah — the divinely appointed author of eternal salvation in the kingdom of God, conjoined with obedience to Christ": πιστεύω τόν υἱόν τοῦ Θεοῦ εἶναι Ἰησοῦν Χριστόν, Acts 8:37 Rec.; ἐπιστεύθη (was believed on (cf. Winers Grammar, § 39, 1 a.; Buttmann, 175 (152))) ἐν κόσμῳ, 1 Timothy 3:16. the phrase πιστεύειν εἰς τόν Ἰησοῦν, εἰς τόν υἱόν τοῦ Θεοῦ, etc., is very common; properly, to have a faith directed unto, believing or in faith to give oneself up to, Jesus, etc. (cf. Winers Grammar, 213 (200f); (Buttmann, 174 (151))): Matthew 18:6; Mark 9:42 (R G L Tr text); John 2:11; John 3:15 R G,; (R G L); ,(),; ,(); ; Acts 10:43; Acts 19:4; Romans 10:14; Galatians 2:16; Philippians 1:29; 1 John 5:10; 1 Peter 1:8; εἰς τό φῶς, John 12:36; εἰς τό ὄνομα αὐτοῦ, John 1:12; John 2:23; John 3:18; 1 John 5:13; τῷ ὀνόματι αὐτοῦ, to commit oneself trustfully to the name (see ὄνομα, 2, p. 448a), 1 John 3:23; ἐπ' αὐτόν, ἐπί τόν κύριον, to have a faith directed toward, etc. (see ἐπί, C. I. 2 g. α., p. 235b (cf. Winers Grammar, and Buttmann, as above, also Buttmann, § 147, 25)): Matthew 27:42 T Tr text WH; John 3:15 L text; Acts 9:42; Acts 11:17; Acts 16:31; Acts 22:19 ((cf. Wis. 12:2)); ἐπ' αὐτῷ, to build one's faith on, to place one's faith upon (see ἐπί, B. 2 a.γ., p. 233a; Buttmann, as above): Romans 9:33; Romans 10:11; 1 Timothy 1:16; 1 Peter 2:6; ἐν αὐτῷ, to put faith in him, John 3:15 (L marginal reading; cf. T Tr WH also (who probably connect ἐν αὐτῷ with the following ἔχῃ; cf. Westcott's Commentary at the passage, Meyer, others)) (cf. Jeremiah 12:6; Psalm 77:22 (), where πιστεύειν ἐν τίνι means to put confidence in one, to trust one; (cf. Mark 1:15 above, β. at the end)); ἐν τούτῳ πιστεύομεν, on this rests our faith (A. V. by this we believe), John 16:30; with the simple dative, τῷ κυρίῳ, to (yield faith to) believe (cf. B. 173 (151)): Matthew 27:42 R G L Tr marginal reading; Acts 5:14; Acts 18:8; supply τούτῳ before οὗ in Romans 10:14; to trust in Christ (God), 2 Timothy 1:12; διά τίνος, through one's agency to be brought to faith, John 1:7; 1 Corinthians 3:5; διά Ἰησοῦ εἰς Θεόν, 1 Peter 1:21 R G Tr marginal reading; διά τῆς χάριτος, Acts 18:27; διά τοῦ λόγου αὐτῶν εἰς ἐμέ, John 17:20; διά τί, John 4:39 (), ; . πιστεύω followed by ὅτι with a sentence in which either the nature and dignity of Christ or his blessings are set forth: John 6:69; John 8:24; John 10:38c R G; ,(); ; (); ; 1 John 5:1, 5; Romans 6:8; 1 Thessalonians 4:14; μοι ὅτι, John 14:11; τί, John 11:26; πιστεύω σωθῆναι, Acts 15:11; the simple πιστεύειν is used emphatically, of those who acknowledge Jesus as the saviour and devote themselves to him: Mark 15:32 (here L adds αὐτῷ); Luke 8:12; Luke 22:67; John 1:50(); f; Rec.; ; Acts 5:14; (); ; (); Romans 1:16; Romans 3:22; Romans 4:11; Romans 10:4; Romans 15:13; 2 Corinthians 4:13; Ephesians 1:13,(); 2 Thessalonians 1:10; Hebrews 4:3; with ἐξ ὅλης καρδίας added, Acts 8:37 Rec.; with a dative of instrumentality καρδία, Romans 10:10; participle present οἱ πιστεύοντες, as a substantive: Acts 2:44; Romans 3:22; 1 Corinthians 1:21; Galatians 3:22; (Ephesians 1:19); 1 Thessalonians 1:7; 1 Thessalonians 2:10, 13; 2 Thessalonians 1:10 Rec.; 1 Peter 2:7; equivalent to who are on the point of believing, 1 Corinthians 14:22, cf. 1 Corinthians 14:24f; aorist ἐπίστευσα (marking entrance into a state; see βασιλεύω, at the end), I became a believer, a Christian (A. V. believed): Acts 4:4; Acts 8:13; Acts 13:12, 48; Acts 14:1; Acts 15:7; Acts 17:12, 34; Romans 13:11; 1 Corinthians 3:5; 1 Corinthians 15:2, 11; with the addition of ἐπί τόν κύριον (see above), Acts 9:42; participle πιστεύσας, Acts 11:21; Acts 19:2; ὁ πιστεύσας, Mark 16:16; plural, ; Acts 4:32; οἱ πεπιστευκότες, they that have believed (have become believers): Acts 19:18; Acts 21:20; (on (John's use of) the tenses of πιστεύω see Westcott on 1 John 3:23). It must be borne in mind, that in Paul's conception of τό πιστεύειν εἰς Χριστόν, the prominent element is the grace of God toward sinners as manifested and pledged (and to be laid hold of by faith) in Jesus, particularly in his death and resurrection, as appears especially in Romans 3:25; Romans 4:24; Romans 10:9; 1 Thessalonians 4:14; but in John's conception, it is the metaphysical relationship of Christ with God and close ethical intimacy with him, as well as the true 'life' to be derived from Christ as its source; cf. Rückert, Das Abendmahl, p. 251. Moreover, πιστεύειν is used by John of various degrees of faith, from its first beginnings, its incipient stirring within the soul, up to the fullest assurance, John 2:23 (cf. John 2:24); ; of a faith which does not yet recognize Jesus as the Messiah, but as a prophet very like the Messiah, John 7:31; and to signify that one's faith is preserved, strengthened, increased, raised to the level which it ought to reach, ; 1 John 5:13b Rec.; (cf. references under the word πίστις, at the end). is applied also to the faith by which one is persuaded that Jesus was raised from the dead, inasmuch as by that fact God declared him to be his Son and the Messiah: John 20:8, 25, 29; πιστεύσῃς ἐν τῇ καρδία σου ὅτι ὁ Θεός αὐτόν ἤγειρεν ἐκ νεκρῶν σωθήσῃ, Romans 10:9 (cf. Buttmann, § 133, 19). Since according to the conception of Christian faith Christ alone is the author of salvation, ὁ πιστεύων repudiates all the various things which aside from Christ are commended as means of salvation (such e. g. as abstinence from flesh and wine), and understands that all things are lawful to him which do not lead him away from Christ; hence, πιστεύει (τίς) φαγεῖν πάντα, hath faith to eat all things or so that he eats all things, Romans 14:2; cf. Rückert at the passage; (Winers Grammar, § 44,3 b.; per contra Buttmann, 273f (235)). δ. πιστεύειν used in reference to God has various senses: αα. it denotes the mere acknowledgment of his existence: ὅτι ὁ Θεός εἷς ἐστιν, James 2:19; acknowledgment joined to appropriate trust, absolutely, Jude 1:5; εἰς Θεόν, John 12:44; John 14:1; equivalent to to believe and embrace what God has made known either through Christ or concerning Christ: τῷ Θεῷ, John 5:24; Acts 16:34; Titus 3:8; 1 John 5:10; ἐπί τόν Θεόν, Romans 4:5; τήν ἀγάπην, ἥν ἔχει ὁ Θεός, 1 John 4:16; εἰς τήν μαρτυρίαν, ἥν κτλ., 1 John 5:10. ββ. to trust: τῷ Θεῷ, God promising a thing, Romans 4:3, 17 (on which see κατέναντι); Galatians 3:6; (James 2:23); absolutely, Romans 4:18; followed by ὅτι, Acts 27:25. ε. πιστεύειν is used in an ethical sense, of confidence in the goodness of men: ἡ ἀγάπη πιστεύει πάντα, 1 Corinthians 13:7. τό πιστεύειν is opposed to ἰδεῖν, John 20:29; to ὁρᾶν, ibid. and 1 Peter 1:8 (Theophilus ad Autol. 1, 7 at the end), cf. 2 Corinthians 5:7; to διακρίνεσθαι, Romans 4:19; Romans 14:1, 23, cf. James 1:6; to ὁμολογεῖν, Romans 10:9.

2. transitively, τίνι τί, to intrust a thing to one, i. e. to his fidelity : Luke 16:11; ἑαυτόν τίνι, John 2:24; passive, πιστεύομαι τί, to be intrusted with a thing: Romans 3:2; 1 Corinthians 9:17; Galatians 2:7; 1 Thessalonians 2:4; 1 Timothy 1:11; Titus 1:8 (Ignatius ad Philad. 9 [ET]; examples from secular authors are given in Winers Grammar, § 39, 1 a.). On the grammatical construction of the word cf. Buttmann, § 133, 4 (and the summaries in Ellicott on 1 Timothy 1:16; Vaughan on Romans 4:5; Cremer, under the word). It does not occur in Revlation, nor in Philemon, 2 Peter, 2 and 3 John (Cf. the references under the word πίστις, at the end.)