The Principle of Contingent Causation: The Impossibility of Infinite Regress.

[polymath257]

I think that your unwillingness to consider the universe as a hypothetical first cause may have more to do with it lacking the properties you believe your god has, than lacking the sort of relationship to contingency and necessity that a first cause is alleged to have.

Answered earlier. Here it re-summarized and expanded upon, 4 Reasons the Universe cannot be the First Cause:

R1: The Universe began to exist. What began to exist exists contingently.

prove it

Therefore, the Universe cannot be the (non-contingent) First Cause.
R2: Further, the Universe was caused by the Big Bang a finite time ago in the past.

That is a bit of a misreading. The Big bang is simply the  properties of the early universe. there is no cause assumed.

Now, what was caused by definition cannot be the First Cause.
R3: Even Further, it is generally agreed the Universe can cease to exist at a Big Crunch event in the future. Again, what can cease to exist is not a Necessarily Existent Being, because what exists necessarily will never cease to exist.

Prove it.

Granted the Universe can, therefore, it is not the First Cause.
R4: Still Further, the Universe began a finite time ago. But we showed in Property I (which none of you have challenged yet AFAIR) that the First Cause had no beginning but exists eternally. Ergo, etc (universe cannot be the first cause). How many more reasons are needed?

You are assuming that time itself is infinite in duration. If, however, time is finite into the past, an event at the beginning of time would qualify as the first cause. It also could not be caused because nothing was prior to it (since time didn't exist prior).

Similarly, if time is finite into the future, it is possible to end and yet still be 'necessary' (in the sense that whenever anything exists, it exists).

In fact, time itself is a pretty good example of something 'necessarily existent': whenever anything exists, time does as well. And everything except time exists within time.

It's not the universe that is the first cause; rather it is the First Cause of the Universe that the Contingency-Necessity Argument proves. B1, contingent on no prior being, existing eternally, not caused by the Big Bang, is therefore not the universe itself, but the First Cause of the Universe.

Let me come to Property IV of the First Cause that makes this even more clear: especially because "potential first cause" was said above, which is ironic, the 4th Property is that the First Cause has no Potentiality, but is Pure Actuality, nothing that He can become that He is already not. 

Property IV of the First Cause: The First Cause has no Potentiality but is Pure Actuality. If some attribute or perfection exists in God, it exists in the highest possible degree, without possibility of decrease or increase.

Prove it. That does not follow from merely being non-contingent.

This is also referred to as the Simplicity of God/the FC. Needless to say, the Universe does not demonstrate this quality.

Proof of Property IV: This is another consequence of His Non-Contingency. It should be observed that beings like man can not only corrupt or decay, can begin to exist and cease to exist, and thereby are called contingent; but further, we can also increase or decrease in various attributes, like power, wisdom, goodness etc - but this is another hallmark of contingency. We have little strength, and we potentially could have much more; these are various contingencies in our being. But in the First Cause, which exists non-contingently, such contingencies like potentialities are impossible. There is therefore no contingency in God/FC; granted that some power and wisdom exists in God, and it clearly had to because He caused the Universe to begin to exist, it follows that God is not merely a powerful being or a wise being, but is Power itself, and the source of all power, and Wisdom itself, and the source of all Wisdom, and so on and so forth with all His attributes (including Goodness, based on Prop III). 

Again, non-potentiality, like non-contingency itself, is not an essential feature of the Universe. Therefore, it is the Cause of the Universe, not the universe itself, that is non-contingent, or non-potential, and thus the First Being in Existence, whom we called B1 in the OP.

Hmm...once again, it looks like the universe as a whole (all of spacetime and all of matter and energy) satisfies these properties: it is necessarily existing, exists whenever there is anything, is the essence of actuality, etc.