[Rathji]

Many religious people think that gay people being on the earth will do one or more of the following:

a) Cause a great destruction to be brought upon by God, like what happened in Sodom
b) Cause moral decay which might impact them negatively on a personal level
c) Spread the 'gay disease' which again, might impact them or their families/friends.

The basic idea, as I see it, is more or less this:

Christians are God's chosen people on earth and need to/are destined to spread the word of his gospel around the whole world. To do this, since gays obviously can't be Christian (I guess?), they need to convert all the gay people since they have a disease/have been convinced/whatever they are being gay.