Says who?Sex is a part of being married and making babies. Having a family - that is the agenda of being married.
The purpose of a marriage is defined by the couple. Who are you to decree what someone else's marriage should be about?
To make this relevant, you would need another passage that says that only people who will inherit the kingdom of God are allowed to marry. Is such a verse even in the Bible?The bible is not silent on this part - men having sex with men - the bible says they will not inherit the kingdom of God so if they will not inherit the kingdom of God where will they be?
Again: not really relevant. You're arguing for why the Bible considers homosexuality sinful. Unless you have some passage about how sinners aren't allowed to marry, the answer you're giving isn't to the question that was asked.Looking for Scripture Explicitly Forbidding Same-Sex Marriage
Romans 1:26-32 New International Version (NIV)
Because of this, God gave them over to shameful lusts. Even their women exchanged natural sexual relations for unnatural ones.
In the same way the men also abandoned natural relations with women and were inflamed with lust for one another. Men committed shameful acts with other men, and received in themselves the due penalty for their error.
Furthermore, just as they did not think it worthwhile to retain the knowledge of God, so God gave them over to a depraved mind, so that they do what ought not to be done. They have become filled with every kind of wickedness, evil, greed and depravity. They are full of envy, murder, strife, deceit and malice. They are gossips, slanderers, God-haters, insolent, arrogant and boastful; they invent ways of doing evil; they disobey their parents; they have no understanding, no fidelity, no love, no mercy. Although they know God’s righteous decree that those who do such things deserve death, they not only continue to do these very things but also approve of those who practice them.
So those are Scripture Explicitly Forbidding Same-Sex Marriage