First off, let me say, that 'un-natural', is not a correct term in this case. If something is un-natural, then it does not occur in nature. Transgender is something that exists, and happens, thus, it is fully natural, as it occurs in nature. (In this, Nature is Existence, by definition.)
I'd also like to point out, if the Creator makes everyone perfect, what about miscarriages, and the countless birth defects?
Or are birth defects an propaganda used by all Atheists to attempt to disprove God? (Now in my own belief, God cannot be proven nor disprove, but this is not a discussion to get into, that is just me.)
The Christian God has given Man (And woman) free-will. As such, even in the minds of a radical, they shouldn't have anything against transgender. As they consider, Transgender is a choice by their belief, so as long as being transgender doesn't harm everyone around us, there's no sin involved. We made out own choice using the gift God had given, Freewill.