Did not Tertullian say, “I believe because it is impossible”?

Yes. But the context shows that he used those words in the sense in which St. Paul spoke of Christ crucified as being unto the Gentiles foolishness. I. Cor. I., 23. He did not mean that he was prepared to believe things repugnant to principles of right reason. There are mysteries in the natural order, and still more there are and must be mysteries in the supernatural order. If God could do only those things which are possible to men, He would be no God at all. But things which are above reason are not necessarily against reason.

Radio Replies Volume 1 by Rev. Dr. Leslie Rumble MSC and Rev. Charles Mortimer Carty