Against Heresies: Book II
Chapter 1: There is Only One God: The Impossibility of Anything Otherwise
It is proper, then, that I should start with the first and most important topic, which is God the Creator, who made the heaven and the earth and all things within them (whom these men blasphemously call the result of a defect), and to demonstrate that there is nothing either above Him or after Him; nor that He was influenced by anyone, but by His own free will, He created all things, since He is the only God, the only Lord, the only Creator, the only Father, alone containing all things, and Himself commanding all things into existence.
How can there be any other Fulness, Principle, Power, or God above Him, since it is necessary that God, the Pleroma (Fullness) of all these, should encompass all things in His vastness and not be encompassed by anyone else? If there is anything beyond Him, then He is not the Pleroma of all, nor does He encompass all. What they claim to be beyond Him will be missing from the Pleroma, or from that God who is above all things. What is missing and falls short in any way is not the Pleroma of all things. In this case, He would have a beginning, middle, and end in relation to those beyond Him. If He has an end regarding things below, He also has a beginning in relation to things above. Similarly, it is absolutely necessary that He experiences the same thing at all other points, being confined, bounded, and enclosed by those existences outside Him. For the being who is the end downwards necessarily surrounds and limits Him who meets His end there. Thus, according to them, the Father of all (whom they call Proön and Proarche), along with their Pleroma and the good God of Marcion, is established and enclosed within some other, surrounded from outside by another mighty Being who must necessarily be greater since what contains is greater than what is contained. But then what is greater is also stronger, and more Lord; and what is greater, stronger, and more Lord—must be God.
3. Now, since they claim there is also something else outside of the Pleroma, into which the higher power that went astray descended, it is necessary that the Pleroma either contains what is beyond it, yet is itself contained (otherwise, it is not beyond the Pleroma; for if anything is beyond the Pleroma, there would be a Pleroma within the Pleroma they claim is outside, and the Pleroma would be contained by what is beyond: and with the Pleroma is understood also the first God); or, they must be infinitely distant from each other—the Pleroma, I mean, and what is beyond it. But if they insist on this, then there will be a third kind of existence that separates by its vastness the Pleroma and what is beyond. This third kind of existence would contain and bound both the others and would be greater than both the Pleroma and what is beyond, as it holds both within itself. In this way, discussion might continue endlessly about those things which are contained and those which contain. For if this third existence starts above and ends below, it must also be bounded on the sides, starting or ending at other points where new existences begin. These, and others above and below, will begin at other points, and so on indefinitely; their thoughts would never settle on one God but, in seeking what is beyond, would stray to what does not exist and depart from the true God.
These remarks can similarly be applied against the followers of Marcion. His two gods would also be separated by an immense distance from each other. This leads to the need to assume a multitude of gods, all separated by vast distances, beginning with one another and ending in one another. By the same logic they use to claim there is a certain Pleroma or God above the Creator of heaven and earth, anyone who wishes to could argue that there is another Pleroma above that one, and another above that, and another ocean of Deity above Bythus, with similar successions on the sides. Thus, their doctrine expands infinitely, and there will always be a need to imagine other Pleroma and other Bythi, never stopping but always seeking more beyond those already mentioned. Furthermore, it will remain uncertain whether those we imagine are below or are actually above, and similarly unclear regarding those they claim are above, whether they are really above or below. As a result, our views will lack any definite conclusion or certainty, but will inevitably wander into endless worlds and an uncountable number of gods.
Given these circumstances, each deity will be satisfied with their own possessions and will not be curious about the affairs of others. Otherwise, they would be unjust and greedy, and would cease to be what God is. Each creation will glorify its own maker and will be satisfied with them, not knowing any other; otherwise, it would justly be considered an apostate by all the others and would receive a well-deserved punishment. It must be that there is either one Being who encompasses all things and created everything within His domain according to His will, or numerous unlimited creators and gods who begin and end with each other in every direction. In the latter case, it would be necessary to acknowledge that all the rest are contained from outside by someone greater, with each confined within their own territory. Therefore, none of them is God, as each would lack much, possessing only a very small part compared to the others. This would effectively bring an end to the name of the Omnipotent, and such an opinion would inevitably lead to impiety.