In regards to the comment regarding founding religions... do you think that if you hit them early and hard enough (with missionaries) you really need to hog all the religions? Don't they serve a purpose by dividing other civs into blocs and preventing their cooperation? Maybe it depends on how many missionaries you are willing to build?
I just depends on who founds what other religions. From what I've seen, the AI's tend to favor a religion they founded themselves over a foreign one.
So if, for example, you have Isabella founding Hinduism, Buddhism, and Judaism herself, then you probably don't need all the others yourself. There are few enough to go around that you can probably convert a few other civilizations to whatever is your religion of choice. Or convert yourself to their religion of choice.
On the other hand, if Hinduism, Buddhism, and Judaism have all been founded by 3 different leaders, then you've got 3 natural blocs formed already. If those leaders happen to be religious kooks like Isabella and/or Brennus, then you have 3 blocs that will hate each other passionately. If you let them found 2 more religions on their own soil, you're just going to see even more splintering.
So at this point we don't know, but I would argue that founding religions ourselves increases the chances that we'll find a bloc of 2 or 3 Hindu (for example) leaders that we can bring over to our side. Letting the AI found the remaining religions increases the chances that we'll find a complete diplomatic mess where everyone hates everybody else.
Since founding the religions also plays into the cultural victory (which I think is probably the easiest and surest path at this point), I'm all for that. Philosophy is on the path to Liberalism too, but Theology would be a diversion if we went for it.