If God gave me a gift then it is now mine. God wanted to give me a gift so why would I want to take that away from him?
Not of myself, hmmm what did God give me? God gave us something and by faith we want to give God something.
If Grace is God's freedom then faith is man's freedom. We could easily replace the word faith with will or love. Yes, how can it be of myself when what I want is of God?
If it's not of myself then is it of Christ in me, the hope of glory? but if Paul spoke about a spiritual process then must things always remain how he defined them to be?
It is clear what a difference between Abel and Cain there was. One was better than the other, one was more righteous than the other. One had more faith than the other.
Spirit, Freedom, faith, will, perception, desire, love... they are all the same thing.