Every time you say “people say being gay isn’t natural, but [insert case of animal homosexuality here], which proves that it’s natural, and anyway we use [insert technology here] which isn’t natural” an angel gets lit on fire.
Okay, probably most of the Christian people who say “being gay isn’t natural” actually mean something along the lines of “being gay doesn’t exist in nature.” That is because most people don’t know what they’re talking about when it comes to Catholic theology. (Also, every time they say that? Two angels.) (If they’re Catholic, anyway. Protestants can say any damnfool thing they like. Damn schismatics.)
“Being gay isn’t natural” is not actually a statement about nature, it’s a statement about natural law. Basically, St. Thomas Aquinas ripped off Aristotle’s idea of the telos, which is basically a thing that any given thing is supposed to do (for instance, knives are made for cutting). He argued that God made everything with a telos and that through reason we can discover the telos of things and then use them in accordance with the purpose God made them for. This is called the “natural law” because you can deduce it from nature, as opposed to the law God revealed.
Catholic theology of the body argues that the genitals have a twofold telos: the unitive purpose (i.e. the bonding of lawfully wedded spouses) and the procreative purpose (i.e. making babies). Every time you have sex, you have to fulfill both teloi, or it violates the natural law. It is, in most circumstances, impossible to have children from homosexual sex; therefore, homosexual sex is immoral. (This is also why the Catholic church opposes birth control. Now You Know ™.)
Now, there are lots of arguments you can make against this thought process, started with “the telos doesn’t actually exist” and moving on from there. “Gay animals exist” is not one of them. Now stop using it, because I have a flamethrower and those angels are fucking trembling.