First off, good animation. Obviously you know that it's rough but you clearly put a LOT of effort into it and that shows. For such a long animation you chose good techniques to make the process of animating more bearable for yourself, but I also noticed those techniques right away (when I saw the old man talking I was like yup he's definitely not moving out of that position for a while)
I think you should have gotten a voice actor for one of the guys. The accent was fine but when the white-looking dude has the accent it tips me off that the voice acting is all done by one dude. The lines were decently delivered, though a little stilted sometimes.
I think what you'll see a lot of is people taking issue with the arguments because they're religious or whatever. A good way to circumvent that is by having more counterarguments emerge that draw what the old man is saying into question. Even if he rebukes all of the pints perfectly the religious side will still feel like they've had their argument heard (it also doesn't help that the conclusion seems to imply that the old man is genuinely correct in believing in god)
I guess what I'm saying is there is a line between where the audience knows that they're listening to a character and where they know they're listening to the creator of the character. We could tell pretty early on that the old man was a self-insert for your ideas, plus a bit of drunkeness. Nobody likes to feel "preached" at, so more characterization of the old man would be good.
I liked the jokes at the end, they were kind of stilted but I got what you were going for. Very much like that the old man was fucking with the business man, fits with the theme of the animation nicely. Keep it up my dude.