Scripture is everywhere clear-the one thing a person must do to be saved is exercise "true saving faith" in Christ. Faith is the instrument that God uses to bring individuals into a saving relationship with Himself. That is not to say that faith is the basis of our salvation; rather, it is the channel by which God grants salvation. Noted theologian B.B. Warfield said, "The saving power of faith resides thus not in itself, but in the Almighty Savior on whom it rests...It is not, strictly speaking, even faith in Christ that saves, but that Christ saves through faith."
Faith comes to the believer as a gift from God. It is not something that individuals are capable of mustering up on their own. Were faith a work of man's own doing, man would be in a position to take partial credit for his redemption. But such a concept is foreign to the writers of Scripture. Paul anticipated that men would tend to boast of their part in salvation when he wrote that faith (one of many components of salvation) "is the gift of God...that no one should boast" (Ephesians 2:8-9). As Charles Haddon Spurgeon was fond of saying, salvation is "all of grace."
Faith comes as a result of the regenerating work of the Holy Spirit-He quickens our hearts to believe. Apart from the new birth, there can be no true faith. Therefore, faith, though it manifests itself in action, comes as a result of God's work in us. God grants us faith and that faith is evidenced by our walking in the good works that "God [has] prepared beforehand" for us to walk in (Ephesians 2:10).
The Bible says that if we believe on the Lord Jesus Christ we shall be saved. However, the Bible does not present faith as simply "mental assent to the facts of the gospel." True saving faith involves repentance from one's sin and a complete trust in the work of Christ to save from sin and make one righteous. The Reformers spoke of three aspects of faith: recognition of the truth claims of the gospel, acknowledgment of their truthfulness and exact correspondence to man's spiritual need, and a personal commitment to the Lord Jesus Christ who, by virtue of His death, provides the only sufficient sacrifice for one's personal sin. Any one of these three aspects of faith, taken by themselves, is insufficient to meet the biblical definition of saving faith. However, the presence of all three components together results in saving faith. In other words, saving faith consists of mental, emotional, and volitional elements. Saving faith involves both the mind and the will.
In addition to calling us to believe on the Lord Jesus Christ, the New Testament uses several figures of speech to describe the nature of saving faith. Perhaps the most vivid of those figurative references is found in Jesus' words from the Sermon on the Mount: "Blessed are those who hunger and thirst for righteousness, for they shall be satisfied" (Matthew 5:6). In that passage, Jesus likens true faith to hungering and thirsting. The unbeliever, by virtue of the regenerating work of the Holy Spirit, recognizes his or her dire need of nourishment and refreshment and comes to Jesus begging that He fill the need. That is a beautiful picture of faith. First, there is recognition of Jesus' claim to be the "bread of life" (John 6:35) and the possessor of "living water" (John 4:10). Next, the unbeliever is convinced that Jesus' promise is really true and that it corresponds exactly with his profound hunger and thirst. Finally, the unbeliever acts-he begs Jesus to satisfy his hunger and quench his thirst. True faith hears, believes, and actively responds.