Anti-gay people: Why is homosexuality a mental illness?

According to the current DSM it is not.

A few decades ago it was, but it has been removed. People couldnt understand why someone would want to engage in that behavior and it was so far from "normal" that it was classified that way, but not today.

I am not judging someones sexuality here. As a hetero male I find the act of two males engaging in sexual intercourse viscerally unappealing. That is my feeling. I dont get it and and I dont even like to think about it. Just like a homosexual person feels about heterosexual activity. A gay man may look at a naked female and be physically repulsed by it. I dont get it, but i dont have to.

For the most part in all of the animal kingdom (with small exception), we do not observe homosexual activity. From a biological point of view, there can be no procreation of the species from homosexual activity.

Anyone reading this who thinks I am bashing gays, i am not. I am simply trying to answer this question as objectively as possible.

According to them, they don't understand it and if it's not the devil it has to be mental illness.