Tertullian — Against Marcion 1.12

For the rest, even if we could confess that he is, we ought to argue that he is without cause. For he would be without cause who had no thing, because every thing is a cause that someone be whose thing it is. Further, inasmuch as nothing ought to be without cause—[that is, without a thing]—because if it be without cause, it is just as if it be not—[not having the thing’s cause, the thing itself]—to that extent I will more worthily believe God not to be than to be without cause. For he is without cause who by not having a thing does not have a cause. But God ought not to be without cause, that is without a thing. So whenever I show him to be without cause, as if he were, I establish this—that he is not—because if he had been, he would not at all have been without cause.

So also I say that he captures faith itself from a human without cause—otherwise than is customary to believe God formed from the authority of works—because he has provided nothing such through which a human learned God. For even if very many believe in him, they do not at once believe with reason, not having God’s pledge, his works worthy of God. And so by this name of cessation and defect of works he is neighbor both to shamelessness and to malignity: to shamelessness, inasmuch as he captures faith not owed to himself, for constructing which he has provided nothing; to malignity, inasmuch as he has made more persons guilty of unbelief by procuring nothing for faith.