Alright, let me get this straight: it's inconceivable that the/a multiverse (or our universe, if you're going to subscribe to something like CCC) had no beginning, thus the only solution is that some other "timeless, changeless, immaterial, and omnipotent" entity caused it?
In my thinking, two issues of our universe need to be explained.
- Our universe had a cause. Pretty intuitive, I don't think anyone disagrees.
- Time had a beginning, whether it began with our universe or outside our universe. I can't remember the name of the argument for this, but I remember how it went. Basically, if the past is infinite, we'd never be in the present, because it would take an infinite amount of time for the past to become the present. Hopefully someone who is better-versed in this argument can help me out.
Our universe's cause can be explained by God, a multiverse, or whatever you want. What is clear is that our universe's cause must be "extrauniversal". Yes my vocabulary's shoddy but I'm working on it and hopefully you get my point. Our universe's cause must be (or must have been, at the time) outside of our universe. And, to go a step further, whatever caused our multiverse must be "extramultiversal". If you really want to get technical, there's a line that stops the otherwise infinite regress of causes, whether that be at the universal level, the multiversal level, or beyond. But for now, I'll just use the word "extrauniversal" as an adjective to describe the first cause to everything.
The fact that time began to exist must mean it had a cause to its existence. Because time did not exist before it was caused to exist, the cause of time existed without time. So, the cause of time is "timeless" (at least when time did not exist).
We can call the cause to time "God". We can attribute to God the qualities of "extrauniversal" and "timeless". In other words, there was an extrauniversal, timeless cause to everything we know today. Something can't cause itself, so God must be these things.
Through philosophy, I agree that we can't call God "changeless", "immaterial", "omnipotent", "omniscient", "loving", "holy", "just" or whatever. That stuff comes with religion. But what is clear is that there exists (or had existed) an extrauniversal, timeless
thing that caused both our universe/multiverse/etc and time.