If someone is religious, how can they be into BDSM?

I would say, try not to mix religion with sex, they don't go so well together

Claiming a religion doesn't really preclude any other type of activities. Heck, even deeply faithful people of the 'mainstream' religions sin on occasion.

Your old boyfriend doesn't seem too odd to me, but you found someone new that you prefer, that's all that matters.

I could understand you not wanting a relationship with someone on drugs or into whatever else, but nobody is perfect. I'm not sure what Celtic Religion is, but when push comes to shove, most religions are aiming for the same thing, Divine Mind. Most people that are affiliated with whatever religion, unfortunately are struggling with something. These are probably some of the things your ex struggled with. Fortunately, you have the option whether to associate yourself with certain people, and the option not to associate yourself with certain people, and you decided to let that go. I try hard not to be judgmental and self-righteous, because I know I have some things about myself, that needs a LOT of work, but at the same time, we all do. It's about how you treat me, and how I treat you, everything else, is between them and God.