Since God has taken my salvation out of my hands into his, making it depend on his choice and not mine, and has promised to save me, not by my own work or exertion but by his grace and mercy, I am assured and certain both that he is faithful and will not lie to me, and also that he is too great and powerful for any demons or any adversities to be able to break him or to snatch me from him. “No one,” he says, “shall snatch them out of my hand, because my Father who has given them to me is greater than all” [John 10:28 f.].
Luther, M. (1999, c1972). Vol. 33: Luther’s works, vol. 33 : Career of the Reformer III (J. J. Pelikan, H. C. Oswald & H. T. Lehmann, Ed.). Luther’s Works (33:III-289). Philadelphia: Fortress Press.
h/t to Mark Latham