You're not studying their religion (studying alone is likely not a clear cut isur anyway), you're exploring what a primitive way of life looks like, whatever their reason is for doing it.
Why does it matter what their reason is? If it's part of their religious belief, it's assur.
I know Rabbi Lebowitz disagrees with Rabbi Veiner on this. But even Rabbi Lebowitz wouldn't allow someone to become an art history major because it's almost all christian art. (just using that as proof that studying is an issue)