Paul writes that For by grace (χάριτι) you have been saved through faith (πίστεως), and this (τοῦτο) is not of yourselves, it is the gift of God; it is not of works, so that no one may boast (Eph 2:8-9).
This is one of the main passages used to show that salvation is not based on what we do but; rather, salvation is an unearned gift. Among other things, this means that no one can boast about deserving to be saved. More specifically, it is often used to emphasize that even our faith itself is not something we posses but rather is given to us: faith ... this not of yourselves ... the gift of God.
The problem with that exegesis of the verse is that this is a neuter pronoun and faith is a feminine noun. While a pronoun's case is determined by its function in the sentence, it gender and number are determined by its antecedent. Therefore, this cannot be referring back to faith. But grace also is feminine, so it cannot be the antecedent of τοῦτο. So what is?
If you looks backwards for an antecedent, you will look in vain. There are neuter nouns, but they make no sense as an antecedent.
The answer is to know a little Greek! When Greek wants to refer back to a general though, perhaps a phrase, the pronoun can be in the neuter. This is not of yourselves does not refer specifically to πίστεως but rather to the entire salvific process, of which faith obviously is a part. It is the entire salvific process that is God's gracious gift and is not part of our own doing. It is a gift.
We often talk about trusting god, that salvation is by faith, but I have often wondered how much people are really able to understand these words. I got to hear my nephew preach this morning, and he did a great job of explaining Eph 2:8-9 (although he never referenced it) using Isa 6. God reveals himself as a holy God. Isaiah's appropriate response was to see the great chasm between himself and God and cry out, Woe is me. Isaiah is forgiven by merely receiving God's atoning gift of the burning goals. Salvation, Dave preached, has to do with seeing God for who he is, with seeing myself for who I am, realizing that there is nothing I can do to move from being a sinner to being holy, and yet also believing that the holy God has done what only he can do in reaching out and offering forgiveness to us. Faith is believing that God has extended the fires of forgiveness.
Isaiah clearly saw that the entire process was a gracious gift received by the faith that believes God has bridged the gap and has forgiven our sins