From peitho; persuasion, i.e. Credence; moral conviction (of religious truth, or the truthfulness of God or a religious teacher), especially reliance upon Christ for salvation; abstractly, constancy in such profession; by extension, the system of religious (Gospel) truth itself -- assurance, belief, believe, faith, fidelity.
see GREEK peitho
1. conviction of the truth of anything, belief (Plato, Polybius, Josephus, Plutarch; θαυμάσια καί μείζω πίστεως, Diodorus 1, 86); in the N. T. of a conviction or belief respecting man's relationship to God and divine things, generally with the included idea of trust and holy fervor born of faith and conjoined with it: Hebrews 11:1 (where πίστις is called ἐλπιζομένων ὑπόστασις, πραγμάτων ἔλεγχος οὐ βλεπομένων); opposed to εἶδος, 2 Corinthians 5:7; joined with ἀγάπη and ἐλπίς, 1 Corinthians 13:13.
a. when it relates to God, πίστις is "the conviction that God exists and is the creator and ruler of all things, the provider and bestower of eternal salvation through Christ": Hebrews 11:6; Hebrews 12:2; Hebrews 13:7; πίστις ἐπί Θεόν, Hebrews 6:1; ἡ πίστις ὑμῶν ἡ πρός τόν Θεόν, by which ye turned to God, 1 Thessalonians 1:8; τήν πίστιν ὑμῶν καί ἐλπίδα εἰς Θεόν, directed unto God, 1 Peter 1:21; with a genitive of the object (faith in) (τῶν θεῶν, Euripides, Med. 414; τοῦ Θεοῦ, Josephus, contra Apion 2, 16, 5; cf. Grimm, Exgt. Hdbch. on Sap. vi., 17f, p. 132; (cf. Meyer on Romans 3:22; also Meyer, Ellicott, Lightfoot on Col. as below; Winer's Grammar, 186 (175))): ἡ πίστις τῆς ἐνεργείας τοῦ Θεοῦ τοῦ ἐγείραντος αὐτόν (Christ) ἐκ τῶν νεκρῶν, Colossians 2:12; διά πίστεως, by the help of faith, Hebrews 11:33, 39; κατά πίστιν, equivalent to πιστεύοντες, Hebrews 11:13; πίστει, dative of means or of mode by faith or by believing, prompted, actuated, by faith, Hebrews 11:3f, 7-9, 17, 20-24, 27-29, 31; dative of cause, because of faith, Hebrews 11:5, 11, 30.
b. in reference to Christ, it denotes "a strong and welcome conviction or belief that Jesus is the Messiah, through whom we obtain eternal salvation in the kingdom of God" (on this see more at length in πιστεύω, 1 b. γ.); α. universally: with the genitive of the object (see above, in a.), Ἰησοῦ Χριστοῦ, Romans 3:22; Galatians 2:16; Galatians 3:22; Ephesians 3:12; Ἰησοῦ, Revelation 14:12; Χρσιτου, Philippians 3:9; τοῦ υἱοῦ τοῦ Θεοῦ, Galatians 2:20; τοῦ κυρίου ἡμῶν Ἰησοῦ Χριστοῦ, James 2:1; μου (i. e. in Christ), Revelation 2:13 (certainly we must reject the interpretation, faith in God of which Jesus Christ is the author, advocated by Van Hengel, Ep. ad Romans 1, p. 314ff, and H. P. Berlage, Disquisitio de formulae Paulinae ψιτις Ἰησοῦ Χριστοῦ signifieatione. Lugd. Bat. 1856); τοῦ εὐαγγελίου, Philippians 1:27; ἀληθείας, 2 Thessalonians 2:13, with prepositions: εἰς (toward (cf. εἰς, B. II. 2 a.)) τόν κύριον ἡμῶν Ἰησοῦν, Acts 20:21; εἰς Χριστόν, Acts 24:24; Acts 26:18; ἡ εἰς Χριστόν πίστις ὑμῶν, Colossians 2:5; (πίστιν ἔχειν εἰς ἐμέ, Mark 9:42 Tr marginal reading); πρός τόν κύριον, Philemon 1:5 (L Tr WH εἰς) ((see πρός, L 1 c.; cf. Lightfoot at the passage); unless here we prefer to render πίστιν fidelity (see 2, below); cf. Meyer at the passage and Winer's Grammar, § 50, 2); ἐν πίστει τῇ ἐν Χριστῷ Ἰησοῦ, reposed in Christ Jesus, 1 Timothy 3:13; 2 Timothy 3:15; τήν πίστιν ὑμῶν ἐν Χριστῷ Ἰησοῦ, Colossians 1:4; ἡ κατά τινα (see κατά, II. 1 e.) πίστις ἐν τῷ κυρίῳ, Ephesians 1:15; ἐν τῷ αἵματι αὐτοῦ, Romans 3:25 (yet cf. Meyer). πίστις (cf. Winer's Grammar, 120 (114)) and ἡ πίστις simply: Luke 18:8; Acts 13:8; Acts 14:22, 27; Acts 15:9; Acts 17:31; Rom. ( c. universally, the religious belief of Christians; α. subjectively: Ephesians 4:13, where cf. Meyer; in the sense of a mere acknowledgment of divine things and of the claims of Christianity, James 2:14, 17f, 20, 22, 24, 26. β. objectively, the substance of Christian faith or what is believed by Christians: τῇ ἅπαξ παραδοθείσῃ ... πίστει Jude 1:3; ἡ ἁγιωτάτῃ ὑμῶν πίστις, Jude 1:20. There are some who think this meaning of the word is to be recognized also in 1 Timothy 1:4, 19; 1 Timothy 2:7; 1 Timothy 3:9; 1 Timothy 4:1, 6; 1 Timothy 5:8; 1 Timothy 6:10, 21 (cf. Pfleiderer, Paulinismus, p. 468 (English translation, ii., p. 200)); but Weiss (Biblical Theol. d. N. T. § 107 a. note) correctly objects, "πίστις is rather the form in which the truth (as the substance of right doctrine) is subjectively appropriated"; (cf. Meyer on Romans 1:5 (and Prof. Dwight's additional note); Ellicott on Galatians 1:23; Lightfoot on Galatians, p. 157). d. with the predominant idea of trust (or confidence) whether in God or in Christ, springing from faith in the same: Matthew 8:10; Matthew 15:28; Luke 7:9, 50; Luke 17:5; Hebrews 9:28; Lachmann's stereotyped edition; Hebrews 10:22; James 1:6; with a genitive of the subject: Matthew 9:2, 22, 29; Matthew 15:28; Mark 2:5; Mark 5:34; Mark 10:52; (Luke 5:20); 2. fidelity, faithfulness, i. e. the character of one who can be relied on: Matthew 23:23; Galatians 5:22; Philemon 1:5 (? see above in b. α.); Titus 2:10. of one who keeps his promises: ἡ πίστις τοῦ Θεοῦ, subjunctive genitive, Romans 3:3. objectively, plighted faith (often so in Attic writings from Aeschylus down): ἀθετεῖν (see ἀθετέω, a.) τήν πίστιν, 1 Timothy 5:12. Cf. especially Koolhaas, Diss. philol. I. et II.de ratio usu et constructione vocum πίστις, πιστόςet πιστεύειν in N. T. (Traj. ad Rhen. 1733, 4to.); Dav. Schulz, Was heisst Glauben, etc. (Leipz. 1830), p. 62ff; Rückert, Com. üb. d. Röm., 2nd edition, i., p. 51ff; Lutz, Biblical Dogmatik, p. 312ff; Huther, Ueber ζωή u. πιστεύειν im N. T., in the Jahrbb. f. deutsch. Theol. for 1872, pp. 1-33; (Lightfoot's Commentary on Galatians, p. 154ff). On Paul's conception of πίστις, cf. Lipsius, Paulin. Rechtfertigungslehre, p. 94ff; Weiss, Biblical Theol. d. N. T., § 82 c. d. (cf. the index under the word Glaube); Pfleiderer, Paulinismus, p. 162ff (English translation, i., p. 161ff; Schnedermann, De fidel notione ethica Paulina. (Lipsius 1880)). On the idea of faith in the Epistle to the Hebrews see Riehm, Lehrbegr. des Hebrew-Br., p. 700ff; Weiss, as above § 125 b. c. On John's conception, see Reuss, die Johann. Theol. § 10 in the Beiträge zu d. theol. Wissensch. i., p. 56ff (cf. his Histoire de la Theol. Chretienne, etc., 3me edition, ii., p. 508ff (English translation, ii. 455ff)); Weiss, as above § 149, and the same author's Johann. Lehrbegriff, p. 18ff