“Therefore shall a man leave his father and his mother, and shall cleave unto his wife: and they shall be one flesh”
This is a must read by Dan Popp asking, “What Did Jesus Say About Homosexuality?” I am sure you will like what it says:
http://www.renewamerica.com/columns/popp/140101
It says that God created them male and female for a reason. Creation involves design, and design reveals intent. Anything outside that design is artificial. It is joining together one man and one woman that conforms to Natural Law of which the Bible is the instruction manual.
The purpose of God’s creation of man and woman is more than the physical one. It is the perfection of his creation because it is also a spiritual one that can only come when the opposite sexes unite and become one flesh. All other methods are artificial and bring spiritual unfulfillment. This perfect spiritual unity is what Jesus spoke about when he called the church as a bride betrothed to him. What a perfect analogy. What God makes he makes perfectly.