As to his religious beliefs, he always struck me as something of a nebulous secular animist; somebody who doesn’t necessarily buy into prayer and miracles and all that, but who appreciates the order of nature as something mysterious and worthy of reverence. That said, a number of his works make direct reference to Buddhist doctrines (which wouldn’t be surprising, as Buddhism is the most popular religion in Japan–even an unbeliever would likely be saturated with knowledge of its tenets).
I certainly don’t think Angel Beats! counts as evidence that he’s some kind of gnostic misotheist, since it seems to take up the position that the question of whether or not a god exists is irrelevant and distracts us from our need to make our own peace through humility and kindness.
I think Maeda-sensei would probably agree with Don Henley saying, “There are no more new frontiers//We have got to make it here”; I think he considers the claim of a post-mortem paradise to be unimportant–what’s important is living life well.