I think the general arguments are;

God said so.
It's dirty.
It's not natural.
Homosexuals corrupt our children!
Homosexuality means less families will be created, and less children raised.

Don't even get me started on countering those stupid arguments.

As an aside, when you consider the bible in it's original context - all those many many years ago - homosexuality would have been frowned upon slightly as no children would have resulted from the union - masturbation was discouraged for the same reason. The penis' function was to create babies.