Okay, let's get a few things straight.

1) I wasn't talking about evil. At no point in my explanation did I say that homosexuals are evil, or that the Church believes such.
2) It's because homosexual acts are unnatural, and unnatural use of the genitals is forbidden by Church law. It's considered abuse of one's body, not unlike self-mutilation.
3) The Church has ~nothing~ at all against homosexuals. They're not intolerant in the least. The Church simply views homosexual acts as wrong.

You don't have to agree with what I'm saying. I'm just trying to present what the Catholic Church believes so people don't have inaccurate views of their beliefs. I'm not saying agree with me - I'm just presenting one side of the argument.