"For by grace you have been saved through faith. And this is not your own doing; it is the gift of God," (Ephesians 2:8)
The Faith that we have is, in and of itself, a gift from God. As explained in Sola Gratia, it is unearned. This is true in both Testaments (See Habakkuk 2:4). Abraham's "righteousness" was imputed to him as a result of his faith (Galatians 3:6-11). The Hall of Faith (Hebrews 11:1-40) testifies to the fact that the Old Testament saints were saved by the same faith that today's saints are.
Faith alone is NOT a defense of antinomianism. Rather by faith we uphold the law (Romans 3:31). Let us hold true to this. We are forever bound to every jot and tittle of God's moral law (Psalm 119:160; Matthew 5:17-18). However, the law cannot save us, but does just the opposite. The law was given "... so that every mouth may be stopped, and the whole world may be held accountable to God. For by works of the law no human being will be justified in his sight, since through the law comes knowledge of sin" (Romans 3:19-20). While it is true that we are “justified by faith apart from works of the law” (Romans 3:28), it is just as true that “faith by itself, if it does not have works, is dead” (James 2:17). Dead faith is not true faith, but merely words. We'll deal more with antinomianism in a future blog, but for now, it is established that the works of the law cannot justify a sinner, but also that faith cannot be used as a license to “practice lawlessness” (Matthew 7:23). Nor can it rightly be said (as many have) that faith is our own contribution to our salvation. For such a teaching would make grace to be, well, not grace. Justification would no longer be by "unmerited favor", but would be a reward rightly owed and paid to us for our faith. But as the opening Scripture tells us, it is by grace through faith alone. "But thanks be to God, that you who were once slaves of sin have become obedient from the heart to the standard of teaching to which you were committed, and, having been set free from sin, have become slaves of righteousness." (Romans 6:17-18)