The belief that Ephesians 2:8-9 says ‘faith is the gift of God’ begs the question: how do human works produce faith? It is not faith that is the gift of God but salvation.
In my Bible Ephesians 2:8-9 reads, “For it is by grace you have been saved through faith – and this is not of yourselves, it is the gift of God – not by works so no one can boast.” I believe the phrase “and this is not of yourselves, it is the gift of God” is really a parenthetical insert. I say this because the sentence is complete without it. “For it is by grace you have been saved through faith, not by works so no one can boast.”
The word translated this (or that) is a pronoun, and rules of grammar state that pronouns normally modify the closest previous noun. Therefore the parenthetical phrase beginning with “this” should modify “faith” making faith the gift. Of course it’s also true that our salvation is a gift in that we did nothing to earn it. I’m just speaking in terms of the construction of the sentence.
The way human works produce faith is similar to the way exercise produces muscle, with one exception. In training, the athlete can only push his body to the limit of his capability, accomplishing all that’s possible for him at that time. As his muscles recover they become stronger, allowing him to accomplish more the next time.
In exercising our faith the Lord asks us to push ourselves beyond our human capability to accomplish the “impossible”. Each time we do that our faith becomes stronger. The Bible contains many accounts of men doing the impossible through faith, and of their faith becoming stronger in the process. Hebrews 11 contains some great examples.