Like repentance, faith too is an essential mark of a Christian. This mark likewise introduces one into the Christian life, being necessary for salvation (Mk. 1:15; Acts 16:30-31; Rom. 1:16-17). Faith, too, is a central characterization of the Christian life.
In Hebrews 11:6 we are told that “without faith it is impossible to please Him, for he who comes to God must believe that He is [exists] and that He is a rewarder of those who seek Him.” In other words, we must believe in the one, true God and His promises. Faith is that which looks toward the things to come: “Now faith is the assurance of things hoped for, the conviction of things not seen” (Heb. 11:1).
In Hebrews 11, which is commonly referred to as the “Hall of Faith” (vv. 7-40), we find this fleshed out. Here we find men and women of God—to include Noah, Abraham, Moses, Rahab, and many others—whose lives were marked by faith in God and His promises. Even though they encountered trials and persecutions, and did not see the full realization of the promises, they yet hoped in God and trusted in Him who rewards. In essence, then, faith is belief or trust in God and His promises.
If you are a Christian then the great object of your faith, (as faith necessitates an object), is the glorious Person and redeeming work of Jesus Christ. The promises of God are “Yes” in Him, and through Him is our “Amen” to the glory of God (2 Cor. 1:20). All that came before, Christ did fulfill; whereas, all that is to come, Christ does secure. A most precious passage of Scripture by which we are reminded that the Christian life begins in Christ and continues in Christ is Colossians 2:6-7: “Therefore as you have received Christ Jesus the Lord, so walk in Him, having been firmly rooted and now being built up in Him and established in your faith, just as you were instructed, and overflowing with gratitude” (cf. Gal. 2:20). Our faith immediately relates to Christ, accepting, receiving, and resting in Him alone for the blessings of salvation—justification, sanctification, and eternal life (Jn. 3:16-18, 36; Rom. 3:21-26; Tit. 3:4-7). The Shorter Catechism defines faith in Christ this way,
Q. 86. What is faith in Jesus Christ?
A. Faith in Jesus Christ is a saving grace, whereby we receive and rest upon him alone for salvation, as he is offered to us in the gospel.
Faith is a gracious gift of God: “For by grace you have been saved through faith; and that not of yourselves, it is the gift of God” (Eph. 2:8).
The fundamental point of all this is that the whole of the Christian life is grounded in a trust in gospel truth and gospel promises.