It is not. Some of it is, to be sure, but there are communities (groups of people in different parts of the world) which are non-religious or are religious of a faith in which the doctrine doesn't expressly forbid homosexuality, yet the same aversion and opposition (in varying degrees) to homosexuality exists. Even in places and times like ancient Rome where homosexuality was celebrated, it was hardly embraced by the populace at large. At most it was grudgingly tolerated. Then there's the question of why such a thing as homosexuality is included in religion in the first place. It's certainly not because of religion. It's because homosexuals give heterosexuals the heebie-jeebies, which is a perfectly natural and normal reaction, which was then incorporated into religion.What strawman? All [modern day] opposition to homosexuals originates from and is legitimized by religion, is it not?
My own [modern day] opposition to homosexuals certainly didn't originate from religion. I fully understand and appreciate that homosexuals are quite natural in the order of things. They exist, always have, and always will. Nothing will change that. The fact that homosexuals exist within nature means that their existence is normal, inevitable in fact. But that doesn't make homosexuality normal by any stretch. It's anormal, goes against the type, against nature despite it being a natural occurrence.
There are countless aberrations within nature that are natural, occurred naturally, yet are not normal. Anomalies are the natural products of evolutionary development, and it is through developmental mechanisms that evolution works. Some go as far as being anormal, such as homosexuality, and an unending list of natural oddities that occur over and over again as part of the evolutionary process. Some anomalies occur more easily, and therefor more frequently than others, like homosexuality, two headed cows, and four leaf clovers.
I understand that some people have a real problem with the fact that homosexuality is basically a birth defect. One group (mainly homosexuals) will take except to it being called a defect, and another group (the ones who completely dismiss the fact that God could make such a blunder of a mistake, over and over again, not to mention dismissing outright the notion of evolution) will rail against it being anything other than a choice of free will. But, what is essentially a defect, is nothing more than nature experimenting with evolution. Sometimes it works, sometimes it doesn't.
Not exactly an argument steeped in religion, is it?