I believe the standard response to people who quote the bit of Levticus they happen to agree with is to ask them if they're also pro-slavery, and anti-people wearing mixed fibres? Do you even keep kosher?

You might also be interested in researching the history of Voodoo, which started out as a synthesis of African beliefs and, yes, Roman Catholicism. (As Terry Pratchett puts it, Voodoo is a do-it-yourself religion, made out of whatever comes to hand.)