As soon as gays and lesbians can have children without scientific intervention, they can get married, until then, they can be lovers/friends/partners, but not married - that is reserved by definition for couples that can, under normal circumstances, conceive children for the survival of the human race.
So, sterile couples can't marry? Or, if you're going to say that's not 'normal circumstances', how about older folks?
All religions have this built into their mantra some place or another.
What's that got to do with the government's definition of marriage? Ever hear of 'separation of church and state'?
States started with the marriage licenses to prevent brothers and sisters from marrying each other. Aside from that, nothing the state does gives a true marriage, they are called civil unions. Go and civil unionize yourselves to your heart's content, it will never be a marriage.
Strawman. Nobody wants religious marriage ceremonies for everyone. But the government has a process that is also known as 'marriage', which is separate and distinct from the religious concept of marriage, and also separate from civil unions, which *do not exist* as far as the federal government is concerned. And because they're not recognized by the feds, they're not covered by the full faith and credit clause, meaning they don't have to be recognized if you go to a different state. In fact, there are currently only four states in the USA that have any concept of 'civil unions' at all. The battle is over 'marriage' because that's what the government calls it. If you want to fight to rename it, go ahead, but that's a totally different battle.
I agree with you in a sense -- the government ought not to have any hand in marriage, or anything like it. But since they do they must offer it indiscriminately. Frankly, they should be required to issue marriage licenses to polygamists and such as well as far as I'm concerned. But religious institutions can continue to do whatever the hell they want -- they have that right as a private organization, and nobody has ever suggested taking that away from them.