Yes. Faith, by grace. God expects us to do works as a sign of faith. I am not qualified nor capable of delineation for what is it isn't the line. I don't like the concept of "once saved always saved" anymore than I like the concept of perpetually earning back your salvation. God forgives me far more than I deserve, and that is grace. Even if it's just my own feelings as a man, I feel I should try and do good because undeserved goodness and mercy and love was shown to me by Christ.