Christian argued that everything must have a creator

[Alex K]

A comment concerning 4,

When quantizing spacetime, it becomes apparent that at the shortest scales, time becomes, if not discrete which would probably be an oversimplification, at least fuzzy and convoluted. It seems very unlikely that it remains - at the shortest scales and highest energies - this apparently smooth and linear thing we have constructed for ourselves. Anyone who tries to argue about causes and caused causes and uncaused causes and god being infinite or finite, or the universe having a beginning, and what was before the beginning, and all that, is not merely barking up the wrong tree, but barking up a shadow of the wrong tree, if you will. All philosophizing concerning these topics by people who don't know modern physics really really well is probably just noise, and the philosophizing from those who do, is basically shooting in the dark.

The situation is made worse by the fact that causality is already a shaky concept within our universe - it is far from clear whether the world doesn't contain true randomness in form of quantum uncertainty.

Also, the arrow of time (which distinguishes past from future) is a purely statistical phenomenon - the future is in the direction of complexity, as illustrated by the increase in entropy - and it could well be that near the origin, time simply connects to another branch that goes into the future again entropy-wise as we go "further back".
A friend has written a paper on this idea recently which got quite a bit of attention. This is their money plot



While their model is a bit of an oversimplification (to say the least) and has been criticized for overselling the novelty of their results a bit, it nicely illustrates a fascinating possibility. Even if we are able to keep a linear timeline through the big bang for some reason, time could be going forward in both directions away from the origin, and what we call causality is reversed accordingly on the other side. (again, of course this is speculation, but viable speculation). Where is your infinite regress of causes of causes if time goes into the future in both directions? Exactly Who knows, maybe time is a star of several lines going into the future from a common point of low entropy. And this is the level of weirdness you can get if you still assume a smooth continuous timeline!

My point is though, not that this must be the correct picture, or even is particularly likely to be the correct picture, but that the rabbit hole goes really deep, and any discussions of causality and time and all those arguments pertaining to the origin of the universe based on notions of linear time and causality, as you find them from apologists and old philosophers, can be safely discarded as uninformed and too naive. Ordinary language of before and after, cause and effect, past and future, moved and unmoved movers, does not capture the potential complexity of the situation even remotely. Likewise, physicists who make confident pronouncements about what happens "before" the big bang, are overselling what is known, because there is just so little data that can be used. Even inflationary models have barely a handful of known parameters that can be measured from the fluctuations in the CMB and extrapolated back, and before that we have nucleosynthesis which afaik doesn't tell us much about quantum gravity, and before that? Since the gravitational fluctuations claimed to be seen by BICEP2, which Matt Strassler alludes to in my quote above, turned out to be a misinterpretation of the data, it doesn't look like we will get a much clearer picture of those things any time soon.