I can give a couple of arguments in favour of the universe having a start point. The first is the one presented in the comic – if there was no beginning, and this universe has always been around, then we would never have reached this present moment in time. If you were to draw a timeline from today stretching back into the past, that line would never, ever end. It just doesn’t make sense to have a universe that never had a beginning.
Even if you imagine some kind of scenario where there were universes before this one – for example, if the universe is born, then dies, then starts over again – you still have the time problem. At some point the whole thing has to have had a beginning, or else we couldn’t be where we are now.
A second argument would be that, in our universe, entropy increases over time (some explanation here) – if entropy is increasing, and over time the useful energy in the universe is running out, then the universe must have had a starting point. If it had existed forever, then all the useful energy would have run out by now.
So – if there was a point before which there was no universe – no time, no materials, and by definition, no scientific processes to cause a universe to pop into being – then how could the universe have gotten started?
Any theory you propose at this point requires a huge leap of faith. The Christian view is that God existed, prior to the existence of everything we see around us, including time itself. He is outside of time, able to set our little universe spinning, with all of it’s laws of physics, and none of which he is bound by. And while that might sound like a cop out, a fairy tale, or a ridiculous leap of faith, for my part it’s honestly the most likely explanation for all this. If it’s between the universe popping into existence out of nowhere without cause, or an act of creation by a sovereign supernatural power, then the supernatural simply seems to be the more reasonable option.