Finally, pistis “can also denote a conviction or certainty of belief.” So, the Lord Jesus speaks of faith which is able to move mountains (Matt. 17:20; Mark 11:23; cf. 1 Cor. 13:2). One of the gifts of the Holy Spirit is faith, which cannot be that which is common to all believers because not all have the same gifts (1 Cor. 12:9; 13:2).
We see that the noun pistis can be used to designate faith in God, in Christ; or the set of doctrine; the certainty of belief. Now we move to the verb πιστεύω (Pisteuo, G4100), which comes from pistis and Thayer defines as “to think to be true, to be persuaded of, to credit, place confidence in” and “to entrust a thing to one, i.e. his fidelity”. According to my Bible software, it is used 217x in the NA28. Mounce observes that
Pisteuo generally means “to believe, be convinced of something,” and in a more specific way “to have faith” in God or Christ. It can also mean to “entrust something to someone.”
So faith and believing (as this is the verb) has to do with having trust and confidence in something or someone. So James Boyce observes about the word faith:
It corresponds with our words, belief and trust,—with belief so far as it refers to the acceptance of facts and statements, or of the veracity of a person,—with trust so far as a person or object is made the foundation of reliance. We believe a fact, a statement, a person; we trust or rely upon that fact, statement or person as something upon which we build. In the one case we have faith in, in the other we put faith in.
Now let us survey the uses of the verb Pisteuo in the New Testament. First of all, Pisteuo can mean to believe or be convinced. So, the Lord Jesus often said to those who wanted to be healed to believe. So in Matthew 9:28, the Lord asks the blind men “Do you believe that I am able to do this?” and they answer with “Yes, Lord.” They are fully convinced that He is able to heal their blindness. In Matthew 8, the centurion, in full faith, says that Christ has only to say the word and his servant will be healed. Christ remarks that “Truly, I tell you, with no one in Israel have I found such faith [πίστιν, pistin]” (Matt. 8:10). Then He says to him, ”Go; let it be done for you as you have believed [ἐπίστευσας, episteusas]” (Matt. 8:13). The centurion had the firm conviction of Christ’s powers and abilities. In John 9:18, the Jewish leaders did not believe the man born blind until they questioned his parents. In John 11:27, Martha is convinced of Christ’s identity as the Son of God and says “Yes, Lord; I believe that [πεπίστευκα ὅτι, pepisteuka hoti] you are the Christ”. So also the disciples know Who Jesus is in John 16:27, 30; 17:8. Pisteuo is also used to express faith in most cardinal matters of Christianity as in the death and resurrection of our Lord. 1 Thessalonians 4:14 says that “we believe that [πιστεύομεν ὅτι, Pisteuomen hoti] Jesus died and rose again”.
In a lot of places, Pisteuo ‘is used to mean “to be convinced of what is spoken or written” (Mt. 24:23, 26; Mk. 16:14; Jn. 4:21; 4:53; 8:46; Acts 24:14; 1 Cor. 15:11)’. Blessed is Mary because she “believed [πιστεύσασα, pisteusasa] that there would be a fulfillment of what was spoken to her from the Lord” (Luke 1:45). The Word of God is also the object of this faith (John 2:22; 5:46-47; Luke 24:26; Acts 24:14; 26:27; cf. Luke 16:31 [not the word for believing or faith])....