Tertullian

For where had been their sin, if they only maintained the righteousness of their own God against one of whom they were ignorant? But he exclaims: "O the depth of the riches and the wisdom of God; how unsearchable also are His ways!" Whence this outburst of feeling? Surely from the recollection of the Scriptures, which he had been previously turning over, as well as from his contemplation of the mysteries which he had been setting forth above, in relation to the faith of Christ coming from the law. If Marcion had an object in his erasures, why does his apostle utter such an exclamation, because his god has no riches for him to contemplate? So poor and indigent was he, that he created nothing, predicted nothing—in short, possessed nothing; for it was into the world of another God that he descended. The truth is, the Creator's resources and riches, which once had been hidden, were now disclosed. For so had He promised: "I will give to them treasures which have been hidden, and which men have not seen will I open to them." Hence, then, came the exclamation, "O the depth of the riches and the wisdom of God!" For His treasures were now opening out.