Wow, really interesting questions and answers, made me registered and would love to say something from China:-)
I guess, if we need to discuss something, we must discuss on the same definition, right?
here, what is religion? if religion is something related to god or gods, something has organization of people and money, something that you have special rules like go to somewhere or read some book(s), then I don't think Buddhism is this kinda religion at all. Actually, it's more like Confucianism or Taolism, maybe as someone already said, it is philosophy. But for me, Buddhism is a daily practice for facing life problems easier, for making yourself and people around you happier.
And for the second question, do anyone here ever wondered 2600 years ago, in a tropic forest, a 29 year young man left his wife and only son, king father, caring mom, palaces and all the fantastic things for what? To escape reality? Later he spent 45 years, with thousands students including his son Rahula and his wife Yasodharā all together. Really, what kind reality he escaped? Maybe, we could spent some time to know this guy and his family more. then we may talk about the other two questions, at least, I need to know your definition on god and Nirvana.
BTW, I also have questions, who asked these 4 questions? what 's the purpose of this essay? Since I don't think Buddha ever declare truth, what he found\taught\practice is just his discovery based on his experience as a human being. Sure anyone could found his own discovery on their own experience. if it works well, you could help people too!
A Lotus for you, a Buddha to be,