Romans 1:26-27 :
For this reason, God gave them up to vile passions. For their women changed the natural function into that which is against nature. Likewise also the men, leaving the natural function of the woman, burned in their lust toward one another, men doing what is inappropriate with men, and receiving in themselves the due penalty of their error.
If people believed in the Creator, they might come to realize that “nature” has an order that was put there by its designer. There are ways to detect this even if you disregard the designer. When a natural system works well it reproduces. When the a natural system deviates from the norm and starts to tear itself down, it may even attempt to guard itself from or remove the thing that is attacking it. When the system is unable to remove that which causes it to grow and live, the system stops or dies.
Mankind reproduces in a natural way too. There are natural passions and unnatural ones. Unnatural ones tear down nature and natural ones build it up. Just because we feel like going against nature doesn’t mean it is ok. We can’t expect to be praised when we go against nature because it is clearly destructive. Homosexuality is a departure from nature. You can’t make children with two men or with two women. A natural family has a man and a woman. Recognizing this gives glory to nature’s designer. Not only is homosexuality not acceptable, the Bible says that such unnatural passions are “vile.”
Why do we want go against nature? Because we are people who have decided to leave our Creator. Sometimes, the training that we received from our parents or schools may have had a part in it, but we add to it just the same. The sins we make affect those around us. If we become proud of these sins we merely continue the attack against the natural and tear down the earth and our environment. Isn’t it amazing that many people fail to recognize that mankind is a part of nature that should be preserved? Ideas that leave mankind out of nature don’t come from the one who made mankind, they come from one that wishes to destroy mankind. Christianity doesn’t believe in going against nature. Instead, it seeks to restore it someday by the power of Jesus.