I saw this on another blog, and thought it was great.

My mother [spoke to me] in those dark hours when the lamp burned dim, when I thought that faith was gone and shipwreck had been made of my soul. “Christ,” she used to say, “keeps firmer hold on us than we keep on him.”
My mother’s word meant...that salvation by faith does not mean that we are saved because we keep ourselves at every moment in an ideally perfect attitude of confidence in Christ. No, we are saved because having once been united to Christ by faith, we are his forever.

J. Gresham Machen: Selected Shorter Writings