Do you tell them to be happy with who they are because you love them & teach all kids to be open & happy with this? Or do you tell them they're wrong because The Bible made marriage between man & woman holy?
I'm not sure who this "them" is you're referring to.
As for what the Bible calls marriage, you really don't want to go there. The Bible, at various points, indicates valid marriage as being between one man and hundreds of women, and allows for a man to purchase a bride as if she were property. Is that really what you think the US should adopt?
Of course GOD blesses some unions between a man and a woman, when they make that vow before God and before friends and family to remain faithful to each other. That is called "holy matrimony," and yes, I believe it is sacred and beautiful. It has nothing to do with what legal rights are granted to a couple by the state. God doesn't give a darn about the state, and, as we all know too well, the feeling is quite mutual. Two people can be wedded in God's eyes and not have a legal, state-acknowledged union (I have several friends who have done this, for various reasons), and two people can be legally married and have no blessing from God for their union. I am lucky enough to have both -- my husband and I were married as part of a Sunday morning service, and we also have a state license indicating that it is a legal marriage. Honestly, I like having both; the tax advantages are not insignificant, but certainly God's presence in our wedded life is most important.
But I digress.
The Bible refers to lots of unions. Jesus does, too. Of course, Jesus didn't use the word "marriage." He wouldn't have even used the Greek term "gamouso" or any form thereof -- he would have spoken in Aramaic, and my Aramaic is a bit rusty. I agree that what Jesus said about marriage is -- or at least should be -- normative for Christians. What I don't understand why so many Christians seem to want to make Christianity the law of the land. This great country was founded on freedom of religion. There are plenty of things that are absolutely sin but not illegal, and should remain so. Gossip, lying (certain cases of lying are illegal, of course -- there's fraud -- but even little white lies are sin, but are perfectly legal), smoking, gluttony, etc. I've never understood why so many Christians seem to think that homosexuality is the one sin that should be banned, whereas these other ones are okay. Maybe it's because so many Christians frequently partake in all those other sins, so they don't consider them as bad as homosexuality. I wonder if God feel the same way, if he ranks sin like that, one being not as bad as another.
Now, as far as what I tell homosexuals, let me say this:
I can tell you that my friends and acquaintances who are not Christian don't hear any words of judgment from me. It is not my job to tell them what is wrong or right. I will, quite frequently, mention my personal walk with Jesus, and talk about how wonderful my life is with Him, but I won't turn it into any kind of "you'd better do the same or else" thing. I've found that you attract more flies with honey than with vinegar. I don't know if my telling them about Jesus has "saved any souls." It's not my job to save the soul, either. That's God's job. Jesus told me to share His story, His Gospel, his Good News, and that's what I do. The rest is up to God, and I am quite happy with that division of labor. I have no desire to encroach upon Jesus' territory.
As far as my close friends who are also Christian, there have been times that I feel I have been called to confront a sister or brother, to call them to accountancy. Jesus tells us we are to watch out for each other, and to help each other in this way. He outlines exactly how to bring up errors to our sisters and brothers, and I have always strived (striven?) to follow these directions. I, too, have been called to accountancy by sisters and brothers in the faith. When it is done out of genuine love, by those who are close, you know that Jesus is in the midst of it.
So let me ask you, what do you tell your friends and/or family, when they eat a little too much, or when they spread gossip about someone, or when they look down on someone as if they were better? Do you tell them to be happy with who they are because you love them? Or do you tell them they're wrong?