One argument often used by Mormons against the biblical teaching of salvation by grace alone is the statement that faith itself is a work and thus, just that alone, proves that we are not saved by grace alone.
But the Bible clearly does not see it that way. It makes works and faith mutually exclusive. “For by grace are ye saved through faith, and that not of yourselves, it is the gift of God: Not of works, lest any man should boast.” (Ephesians 2:8-9) That passage makes no sense if faith is a work. Although some try to qualify the works in this passage to say that “works” refers to a certain type of works like the works of the Old Testament, Paul doesn’t qualify it.
If that isn’t clear enough, there is Romans 11:6. “And if by grace, then is it no more of works; otherwise grace is no more grace. But if it be of works, then it is no more grace, otherwise work is no more work.” If faith was a work then we are not saved by grace because works and grace don’t mix.
From the biblical perspective, faith is not a work. The work that saves us has all been done by Jesus. He paid the full price of our sins. He kept the law perfectly for us. Salvation is God’s gift to us. “For by grace are ye saved through faith, and that not of yourselves, it is the gift of God: Not of works, lest any man should boast.” (Ephesians 2:8-9)