How does not having religion make it any easier to balance?
You're free to join any religion if you want to. There's no "game imba" associated with that.
You clearly have no idea of the impact religion has in Civ 4 if you think there is no balance associated with it. They are probably also trying to balance it in a more meaningful manner than Civ 4's implementation, which was fairly simplistic (your choices were essentially to join the religion of your nearest neighbor to avoid hostilities, or form your own religion and spread it everywhere as a means of building a massive gold income that comes from having the dominant world religion plus some wonder). There are other minor nuances to it that come in to very high level play, but for the vast majority of gamers it was nothing more than that, and that requires balance, and some extra features built in around the concept of religion sure as fuck wouldn't hurt. So in essence your quite is ridiculous.
I know you didn't specifically mention espionage, but the post you referenced did, and espionage is even more of a balance issue to deal with. It was never implemented that well even at the end of BtS's life cycle - low level players were constantly abused by non-stop harassment from enemy espinonge attacks that they had no idea how to deal with, and high level players constantly abused the fact that you could drop a cities defensive power down to 0 with a single spy because the AI couldn't properly defend against it. On top of that, the AI was programmed so poorly to USE espionage that it CONSTANTLY wasted resources and its espionage points on useless spy missions which were nothing but a small bother to any intermediate player.
The point is these systems existed in Civ 4 in very flawed forms (with the general consensus being that bad players didnt understand them, and good players could just abuse the mechanics of it), and while we don't even know yet how they will be implemented in to Civ 5, there are a LOT of considerations that SHOULD be going in to how these mechanics are implemented in Civ 5. We can only HOPE that Firaxis doesn't take just a stupid approach to it as "just implement the way it was in Civ 4 HERP DERP"