Mixing in other religions with buddhism?

I've heard this for Christianity but not for other faiths. Can an individual be of a different religion and simultaneously be buddhist? If not mainstream than some other tradition? (pagans, hermetics, bahais, so on) I ask this because I've always had interests in all religions and kinds of faiths, and even though I've experimented between some I find that it can be restraining to just stick to a single path (maybe not for you but certainly for me)

I understand that some religions have less wiggle room than others and I don't want to dissolve buddhism down to just a philosophy.