Cairns defines faith “as the work of the Holy Spirit, His gift to God’s elect, enabling them to believe as true whatever God has revealed in His Word and to accept, receive, and rest upon Christ alone for justification, sanctification, and eternal life. It is never alone, being always accompanied by repentance and producing good works.”
Charles Ryrie states, “Faith means ‘confidence, trust, holding something as true.’ Certainly, faith must have some content. There must be confidence about something or in someone. To believe in Christ for salvation means to have confidence that He can remove the guilt of sin and give eternal life. It means to believe that He can solve the problem of sin which is what keeps a person out of heaven.”
When writing about faith in relation to salvation, Charles Hodge states, “That faith, therefore, which is connected with salvation, includes knowledge, that is a perception of the truth and its qualities; assent, or the persuasion of the truth of the object of faith; and trust, or reliance. The exercise, or state of mind expressed by the word faith, as used in the Scriptures, is not mere assent, or mere trust; it is the intelligent perception, reception, and reliance on the truth, as revealed in the Gospel.”
Critical to understanding the biblical definition of faith in connection with salvation is, understanding the three elements that are part of that definition:
(1) Faith is knowledge. By this we mean that faith knows the facts about something or someone, it rests upon evidence rather than it being a blind act taken because of a lack of knowledge (Ps. 9:10; Rom. 10:17).
(2) Faith is assent. In other words, knowledge of the facts results in believing those facts. Knowledge becomes conviction; knowledge goes from being mental to being heartfelt.
(3) Faith is trust. This means we appropriate those convictions and completely surrender and submit to the object of our faith. Trust is giving consent to the will to take action, to move, embrace, and receive (John ) without reservation the Christ it believes. Faith takes us from knowledge about Christ to belief in Christ.
The Bible is very clear in teaching that God is the source of faith, faith is a gift (Rom. 12:3; Phil. 1:29), and it is given to those who do not resist the Holy Spirit who creates it in the hearts of men, leading them to repentance and enabling them to trust. The result of faith is salvation (John ; Rom. 5:1; Gal. ).
, Dictionary of Theological Terms, expanded third edition ( Cairns : Ambassador Emerald International,
2002), p. 175. Greenville
 Charles C. Ryrie, So Great Salvation (Wheaton: Victor, 1989), pp. 118, 119.
 Charles Hodge, Commentary on the Epistle to the Romans (Grand Rapids: Eerdmans, 1967), p. 29.