the faith that God has enjoined on you? For what end did it serve to send His Son to suffer and to be crucified for us? Of what use was it to institute the sacraments if they are uncertain or completely useless for our salvation? For otherwise, if someone had been predestined, he would have been saved without the Son and without the sacraments or Holy Scripture. Consequently, God, according to the blasphemy of these people, was horribly foolish when He sent His Son, promulgated the Law and the Gospel, and sent the apostles if the only thing He wanted was that we should be uncertain and in doubt whether we are to be saved or really to be damned.
But these are delusions of the devil with which he tries to cause us to doubt and disbelieve, although Christ came into this world to make us completely certain. For eventually either despair must follow or contempt for God, for the Holy Bible, for Baptism, and for all the blessings of God through which He wanted us to be strengthened over against uncertainty and doubt. For they will say with the Epicureans: “Let us live, eat, and drink; tomorrow we shall die” (cf. 1 Cor. 15:32). After the manner of the Turks they will rush rashly into the sword and fire, since the hour in which you either die or escape has been predetermined.
But to these thoughts one must oppose the true and firm knowledge of Christ, just as I often remind you that it is profitable and necessary above all that the knowledge of God be completely certain in us and that we cling to it with firm assent of the heart. Otherwise our faith is useless. For if God does not stand by His promises, then our salvation is lost, while, on the other hand, this is our comfort, that, although we change, we nevertheless flee for refuge to Him who is unchangeable. For in Mal. 3:6 He makes this assertion about Himself: “I the Lord do not change.” And Rom. 11:29 states: “The gifts and the call of God are irrevocable.” Accordingly, this is how I have taught in my book On the Bondage of the Will and elsewhere, namely, that a distinction must be made when one deals with the knowledge, or rather with the subject, of the divinity. For one must debate either about the hidden God or about the revealed God. With regard to God, insofar as He has not been revealed, there is no faith, no knowledge, and no understanding. And here one must hold to the statement that what is above us is none of our concern. For thoughts of this kind, which investigate something more sublime above or outside the revelation of God, are altogether devilish. With them nothing more is achieved than that we plunge ourselves into destruction; for they present an object that is inscrutable, namely, the unrevealed God. Why not rather let God keep His decisions and mysteries in secret? We have no reason to exert ourselves so much that these decisions and mysteries be revealed to us.
Moses, too, asked God to show him His face; but the Lord replies: “You shall see My back, but you will not be able to see My face” (cf. Ex. 33:23). For this inquisitiveness is original sin itself, by which we are impelled to strive for a way to God through natural speculation. But this is a great sin and a useless and futile attempt; for this is what Christ says in John 6:65 (cf. John 14:6): “No one comes to the Father but by Me.” Therefore when we approach the unrevealed God, then there is no faith, no Word, and no knowledge; for He is an invisible God, and you will not make Him visible.
Furthermore, God has most sternly forbidden this investigation of the divinity. Thus when the apostles ask in Acts 1:6, “Has it not been predestined that at this time the kingdom should be restored?” Christ says to them: “It is not for you to know the times” (Acts 1:7). “Let Me be hidden where I have not the