So no one has ever asked you to attend a same sex marriage, let allone ordered you to marry someone of the same sex.
So your first reason to disapprove of same sex marriage if falsified.

I fail to see a non-bigot reason to oppose of same sex marriage and granting gay people equal rights. It seems to me you don't know any gays (your second "reason" seems to indicate that). Because if you did know any gay people and you made an effort to listen to the reasons why they want to get married, you would find out they want to get married for the same reasons heterosexuals want to get married.

The 'deportatoin to Siberia'-reference is here nor there. 'Deportation' = forced to move. Nobody is forcing anybody to have a same sex marriage (or even attending one). If someone would decide to move to Siberia, who am i to tell them they can't. If someone wants to marry someone of the same sex, they should have that right (if both partners are adults and agree to marry each other).

Your second statement is also here nor there. Everyone has the right to have doubts about things. Sure, a lot of people have doubts about their sexuality. Science haven't found "the answer" to the question how people turn out to be gay of straight. There are indications it's genetic, but it doesn't realy matter how come some people are straight and others are gay. What matters is that everyone should treat other people with respect. Forcing your religious believes upon others is indeed bigotery. If the superbeing you choose to believe in doesn't agree with same sex marriage, that's fine, so don't marry someone of the same sex. But other people have other believes and the laws of a nation with freedom of religion shouldn't be based on the rules of 1 religion. Saying gay people can't get married because it's against your religion is like saying eating candy should be prohibited because you're on a diet.

If your brother would want to get married to his partner, a good brother would support that right. I wouldn't dream of denying my brother or other people i care about the same rights I have. One should treat others as one would like others to treat oneself.

No one is forced to marry someone of the same sex. And as far I know there not attending a marriage is not illegal. Just saying "not true" doesn't falsefy my statement. Without any proof people are forced by law to marry someone of the same sex my statement still stands.

Reverse therapies have proven not to work and even be harmfull (surpression on ones true nature leads to depression and even suicide). If someone has doubts about his/her sexuality the right help is to help that person find his true sexuality, not forcing him of her in the way of your religion. Homosexuality is not an illness that should surpressed or cured. More and more states outlaw reverse therapies because they are dangerous. Reverse therapies can be deadly, accepting yourself is the key to wellbeing. Persute of happiness and stuff...

Dueling can result in murder. Except in the case of euthanasia killing someone is illegal, because it harms other people. Same sex marriage doesn't harm anyone, not being allowed to marry your partner does harm.

Your diet isn't banned, you still can follow your diet (marry someone of the opposite sex). Same sex marriage didn't outlaw opposite sex marriage.

Granting other people the same rights you have has noting to do with religion, but everything with respect. Respect for each other is one of the corner stones of civilasation. Denying other people the same rights you have is a sign you think your superior then them. Everyone should be treated equaly, i think there is something like that in the constitution of the USA, it sure is in the Universal Declaration of Human Rights.
True, some aspects of religion that are harmfull to others has been made illegal (like killing people because they have a different oppinion), but thats hardly a violation of religious freedom, is it?

Before judging gay people and denying their rights try to walk a few miles in their shoes.