Same sex marriage: 
Think about what marriage is In all cultures (that I know of - I'm pretty sure someone will find some obscure culture that's different), marriage is a union between a man and woman to create the next generation, and live out their lives together. Marriage isn't something to be taken lightly. Of course, in today's liberal world, it's "everthing goes, because it's humanly (physically) possible". Just because it's possible to do something, doesn't make it right. It's also immoral. You can rationalize it away if you want, but you're only turning your head away from the truth.
What makes it immoral?
Same sex adoption:
I wouldn't approve of it. It's taking a child into an immoral lifestyle. Plus, the child's gonna wonder where they came from, and will ask questions why they have two mommies or two daddies.
Again, what is immoral in it?
Legalizing marijuana:
Why? So more people can get high? Even if it's for "medicinal uses", the risks outweigh any benefit.
It does have some real medicinal uses, but I don't support legalising it.
Euthanasia:
Killing off the old people will only lead to a slippery slopes of killing off babies born with disabilities -- hmm, wait, that's already being done. (abortions)
What if they [old people/with terminal diseases] want to die? Do we have a duty to live?
Stem (cell) research:
As long as it comes from cells of an unborn baby that's killed (harvested) for their cells, then no.
IV fertilisation causes that, I suppose you oppose it too. When does an embryo become human? I think it's a bit naive to think that fertilisation does it, as it's a bit like ranking human lives and all other animals the same moral value. You can do it, but there's always the but.
Capital punishment:
No, except for the most severe and extreme of cases.
What would make killing right? All punishments are sometimes given wrongly, and this is the only irreparable one. Also capital punishment is a really justified punishment only with the assumption of life after death, which mustn't be assumed by the justice system.
Legalizing Prostitution:
Ummm... why? Must be a male thing.
Slave trade and organised crime are heavily connected with prostitution. Increase in prosperity results in decrease in prostitution, showing that many people wouldn't be prostitutes if they could gain money with other ways.
Abortion:
Absolutely not! There's other alternatives, like giving up the baby for adoption. There can be support in schools or whatnot when a pregnacy does happen. (It's never "unexpected", because when you choose to have relations with another man, it's bound to happen) Also, abstinence over condoms. Condoms is another nono.
How about criminally caused pregnancies? Rape, incest? Some people would get abortions anyway, and die because of that. And what is wrong with condoms?
