I was raised Protestant but after years of searching, I practice Zen Buddhism. The teachings about letting go of material attachments, being mindful and the interconnectedness of all living beings ring true to me more than the teachings of any other religion do. My heart tells me it's true and I've learned that the more I listen to my heart, the happier I am.
I believe any religion, practiced with a kind, open and mindful heart, can be a path to spiritual fulfillment--and a better world.
Over the years (and still today), too many people have used religion for selfish purposes which have little (if anything) to do with spiritual fulfillment and much (if not everything) to do with manipulating and controlling people for money, power (etc).
I think this hijacking of religion is why so many are skeptical/cynical/apat hetic about religion. If there is such a thing as sin, using religion for selfish purposes has to be among the worst, I'd say...