Wow, what a lot of answers you got in just 3 days?
Personally I am Jewish, but not religious enough to know if it is forbidden by my religion, although I suspect so.
My experience has been that learning how to read the cards and reading itself has made me a more religious person. In the sense that I was brought up by two atheists, but my experiences with my cards have shown me SO many things that could not possibly be mere coincidence. My cards have cemented my belief in a higher power, in G-d. I don't believe I would have ever gotten to this point without Tarot, in fact I know I would not have.
As well experiences I have had with my cards, have taught me to beleive in angels (and they are an enormous presense in my life now), as well as faeries.
So what so many religions frown on for me has turned an agnostic into a believer and someone who believes life just happens to her to someone who has tools to co-create my life. Although, in another sense, the cards have lead me to develop my own personal sense of spirituality,with parts borrowed from different religions. They have taught me to believe in reincarnation, for one, and that is not a true part of my religion, in the way I beleive in it now.
It's lead me to explore different spiritual concepts and taught me some are right for me and others are not, whether or not they belong to the religion I am in.
In that sense, I can see why a particular religion might not like a tool that might encourage you to find your own truths. Religions want you to believe in all that they embrace, not pick and choose.
My cards are my greatest tool for creating my future, my tool to clarify confusion and to sooth any pain in my life. They're I guess you could say one of my greatest coping tools. Not to mention my career to some extent as I am just starting out as a professional. I can't imagine my life without them, it would be....less.
Babs