Is cherry-picking natural?

I was listening to a debate on the radio the other day between a Christian arguing against same-sex marriage and another person pointing out the irrationality of that position. The religious person kept repeating the same phrase at the end of every exchange, "it's not natural" she kept saying. I suspect this person thinks that homosexuality doesn't exist in nature and/or that the only purpose of sex is procreation. Clearly, it's difficult for someone to be so wrong along so many dimensions at the same time and remain sincere, it became clear that the Christian had no rational arguments for her position at all, none, listeners were left concluding that either this person was a bigot and/or homophobic or that she blindly believed every literal word of her holy book and expected everyone else to follow suit (by law!).

It's always amused me how religious literalists choose to cherry pick what they literally believe from their holy books, books that claim homosexuality isn't natural (it exits all over nature) and yet talking snakes and flying horses are just dandy; and they claim not to see any problem with this...