So, you are claiming that any "prolonged spiritual practice" will do? Will achieve the same results? That whatever this deity is it doesn't care at all what someone does or believes as long as they are devout about it?
A religion is a set of beliefs regarding our very spiritual existence, often including some form of deity and ritualistic practices of some kind. Now, there are many many religions in the world, both past and present. Many of which contradict each other on what one should believe, what one should do, and repercussions of not doing one or both. All religions cannot be true. It is, frankly, impossible. Now, all religions may hold a bit of truth within them, but they are certainly not all "true". And just because it may well be that all spirits end up the same place it still does not mean that all paths speak "truth", just that the "truth" is that religion, belief, deity...none of it matters anyway.