Tertullian, Against Marcion 12

Even if we could admit He exists, we would still have to argue that He exists without cause. Anything without cause lacks a thing, because every thing is a cause — it exists so that there is someone whose thing it is. Since nothing ought to be without cause, that is, without a thing — for if it is without cause, it might as well not exist — lacking the cause of a thing means lacking the thing itself. To that extent, I judge it more fitting for God not to exist than to exist without cause. He is without cause who, by not having a thing, has no cause. But God ought not to exist without cause, that is, without a thing. So every time I demonstrate that He exists without cause, as if He exists, I prove He does not exist — because if He had existed, He would not have existed without cause at all.

Thus I also say that faith seizes Him without cause from man. Normally one believes in God shaped by the authority of works. But He foresaw nothing of the kind through which man might learn of God. Even though many believe in Him, they do not believe by reason straightaway. They lack God's pledge, His works worthy of God. And so, under this name of cessation and defection of works, of impudence and malice, He is kin to impudence — which snatches faith not owed to Him, for whom He foresaw nothing to be laid out — and to malice — which made many guilty of unbelief, securing nothing for faith.