Luther on Predestination
"Concerning predestination, it is best to begin below, at Christ, as then we both hear and find the Father; for all those that have begun at the top have broken their necks. I have been thoroughly plagued and tormented with such cogitations of predestination; I would needs know how God intended to deal with me, etc. But at last, God be praised! I clean left them; I took hold again on God?s revealed Word; higher I was not able to bring it, for a human creature can never search out the celestial will of God; this God hides, for the sake of the devil, to the end the crafty spirit may be deceived and put to confusion. The revealed will of God the devil has learned from us, but God reserves his secret will to himself. It is sufficient for us to learn and know Christ in his humanity, in which the Father has revealed himself." Martin Luther, Table Talk, DCLVII.
Machen on the Law and the Gospel
“‘The law is not of faith (does not partake of the nature of faith), but as Scripture says, ‘He who does them shall live in (or by) them.’ Paul means to say, “describing the nature of the law, it requires doing something. But faith is the opposite of doing. So when the Scripture says that a man is justified by faith, that involves saying that he is not justified by anything that he does. There are two conceivable ways of salvation. One way is to keep the law perfectly, to do the things which the law requires. No mere man since the fall has accomplished that. The other way is to receive something, to receive something that is freely given by God’s grace. That way is followed when a man has faith. But you cannot possibly mingled the two. You might conceivably be saved by works or you might be saved by faith; but you cannot be saved by both. It is ‘either or’ here not “both and.” – J. Gresham Machen, Notes on Galatians p. 178
Walther on trusting your conversion instead of Christ
"We are not to look back to our conversion for assurance, but we must go to the Savior again and again, every day, as though we had never been converted. My former conversion will be of no benefit to me if I become secure. I must return to the mercy-seat every day, otherwise I shall make my former conversion my savior, by relying on it. That would be awful; for in the last analysis it would mean I make myself my savior." C. F. W. Walther, The Proper Distinction of the Law and the Gospel p. 207