One defining element of most conventional religions seems to be a yearning for something more, as it were, whether it be a union with some deity, or an existence in another reality. Basically, anything that isn't here and now. Is this world we live in really that bad?
I am a child of the 20th century, of the age of science. Whether I want to or not, I can't help but view the world in empirical terms. If I don't see it or experience it, I have no way of knowing it really exists, and, frankly, I have no time to waste on uncertainties. I see no point in praying to get to Heaven (and even less in living my life according to some arbitrary rules for that same purpose), or trying to achieve Nirvana (whatever that even is, most Buddhist philosophy just goes way over my head).
(Note: I'm not saying that such practises may not be beneficial, or 'right', for other people. As I see it, there is no such thing as a 'correct' religion or spiritual path, and there never can be. Each of us react differently to various teachings and philosophies, and what appears ridiculous to some of us may well be powerful and genuinely helpful to others.)
But the great dilemma is, what value does spirituality hold if the physical world is all there is?
Well, we must remember that this 'physical' world contains such amazing and awe inspiring things as the human brain. Somewhere in that mess of neurons are born an endless number of symbols and concepts, which even somehow manage to bounce around between individual brains, and seem to almost live a life of their own.
Every god and spirit created by Man is real, because 'mere' concepts clearly have genuine power over us. The methods of spirituality do have a rational, real basis. Symbols and ritual affect us in a profound way. It's called 'psychology', you might have heard the word sometime. So the methods are sound, even in a materialistic, rational, empirical world. But motivation is of course a whole other matter.
The simple answer to the dilemma: If you are able to change your life (and the world), for the better, by any means, isn't this worthwhile? (Oh, and of course there's an even simpler answer: It could be fun!)
But the brain is a tricky customer. No matter how well you rationalise the value of symbols and ritual, it may be difficult to trust something that appears to have no basis in this material world. There really is no easy solution to this dilemma, except maybe to just ignore those feelings as best you can and perform rituals anyway. Who knows, maybe they'll go away after a while.
Hesitating will get you nowhere, that's for sure. A long time ago, a wise magus said: 'Do, or do not. There is no try.' At least as far as spirituality and magick are concerned, I'm inclined to agree.