After this Celsus relates at length opinions which he ascribes to us, but which we do not hold, regarding the Divine Being, to the effect that “he is corporeal in his nature, and possesses a body like a man.” As he undertakes to refute opinions which are none of ours, it would be needless to give either the opinions themselves or their refutation. Indeed, if we did hold those views of God which he ascribes to us, and which he opposes, we would be bound to quote his words, to adduce our own arguments, and to refute his.
But if he brings forward opinions which he has either heard from no one, or if it be assumed that he has heard them, it must have been from those who are very simple and ignorant of the meaning of Scripture, then we need not undertake so superfluous a task as that of refuting them. For the Scriptures plainly speak of God as of a being without body. Hence it is said, “No man has seen God at any time;” and the First-born of all creation is called “the image of the invisible God,” which is the same as if it were said that He is incorporeal. However, we have already said something on the nature of God while examining into the meaning of the words, “God is a Spirit, and they who worship Him must worship Him in spirit and in truth.”
Source: Against Celsus (New Advent)