The definition of marriage is important. If my kids ask me if they will ever be married, if I say probably, I don't want that to mean it could be to someone of their own sex.
That is not acceptable.
When the TV news announced the recent superior court ruling in CA on homosexual marriage, I mentioned to my daughter, who is 13, that if society redefines marriage to apply to a union of homosexuals, the institution of marriage will be virtually meaningless. I was sad to hear her reply: that many children at her middle school already believe that marriage is a meaningless institution. This does not bode well for the future of our society.