Ephesians 2:8-9 deals a death blow to man's pride and vaunted powers: "For by grace you have been saved through faith; and this is not from you: it is the gift of God, not from works, that no one should boast." The "and this" in verse 8 is neuter and singular in the Greek. The syntactical problem here is that there is no neuter antecedent, which is unexpected. Both grace and faith are feminine and singular in the Greek, and the periphrastic participle rendered "you have been saved" (or "you are being saved") is masculine and plural. So what is the antecedent? Oftentimes "and this" has a conceptual antecedent in the New Testament. And that seems most fitting here in Eph. 2:8-9. So the antecedent is a by-grace-through-faith salvation. None of it is from man: all of it is the gift of God. And, yes, this includes our faith. It too is a gift of God.
Why, one might ask? Does it have to be taken that way? I think that grammatically it makes the most sense, though the grammar is not decisive. Context and theology are! There is another factor in the context
—God's aim. God is bent on ensuring that no one might boast (v. 9) in the way he bestows salvation. Leaving a little room for man to glory in his self-generated faith would devastate God's purposes in salvation. If the decisive factor when a person comes to faith in Christ is self-generated faith
—to any degree whatsover
—then man is decisive, even if he says he is only receiving the free gift, and has reason for glorying in self. If salvation hangs ultimately on man's decision, upon whom does it ultimately rest? Yep, you got it. And it's disgusting, isn't it? God will have none of it. So the whole of his by-grace-through-faith salvation is a gift
—including the faith
—that none should boast.
Except, in the cross of Christ and the free grace of God.