37 And if you ever fall into disputation and have not the grounds of proof, yet let Faith remain firm in you; or rather, become thou well learned, and then silence the Jews out of the prophets, and the Greeks out of their own fables. They themselves worship men who have been thunderstricken: but the thunder when it comes from heaven, comes not at random. If they are not ashamed to worship men thunderstricken and abhorred of God, are you ashamed to worship the beloved Son of God, who was crucified for you? I am ashamed to tell the tales about their so-called Gods, and I leave them because of time; let those who know, speak. And let all heretics also be silenced. If any say that the Cross is an illusion, turn away from him. Abhor those who say that Christ was crucified to our fancy only; for if so, and if salvation is from the Cross, then is salvation a fancy also. If the Cross is fancy, the Resurrection is fancy also; but if Christ be not risen, we are yet in our sins. If the Cross is fancy, the Ascension also is fancy; and if the Ascension is fancy, then is the second coming also fancy, and everything is henceforth unsubstantial.
Source: Catechetical Lectures (New Advent)