In 1999, researcher Bruce Bagemihl showed that homosexual behavior has been observed in close to 1,500 species, ranging from primates to gut worms, and is well documented for 500 of them and in many creatures that do not have the conscious capacity to think.That was almost 13 years ago. Why again do you still say homosexuality, in you’re words "unnatural?"
The definition of what is "natural" for a human being is highly debatable, of course. By definition, anything an animal does is "natural," because they are not self-aware and do not have consciousness as humans do (I am aware that this is debatable as well).
Having acknowledged that the defintion is highly debatable, I believe that heterosexuality is natural to humans for a few reasons. First of all, the physiology is quite clear. I assume you do not need me to give the details. The male sexual organs are extremely well designed, both to stimulate the female organs and, obviously, to fertilize the female. Male-with-male intercourse is not "natural" by that definition. It is in fact very dangerous in terms of causing infection and passing along various diseases. Of course, it is possible to spread diseases by the "natural" form of intercourse, but the likelihood is way lower and heterosexual intercourse serves a purpose other than simple pleasure and bonding, which is to perpetuate the species.
Some might say that if it feels good, it is natural. I disagree with this. Drunkenness, orgies, pornography, violence, other criminal acts may feel good, but, on the whole, they are destructive. Therefore, the ability to produce pleasure does not fit my own personal definition of what is "natural." Of course, you do not have to accept my definition. I believe that, on the whole, homosexual relations are hurtful to the human species and to individuals. I understand that some individuals will have a big problem with this statement, but this is my personal conclusion.
Then there is God’s say in this. I accept that the Bible is inspired by God. I do so because of the massive evidence in support of this. If God says an activity is sinful and an abomination, then I am prepared to call it unnatural. I understand that this is a rather arbitrary definition of natural. Is heterosexual adultery "natural" and homosexual adultery "unnatural?" I will freely admit that my definitions are not on extremely solid footing here. Again, you will have to reach your own conclusions there. But, back to the Bible. In Romans 1:26 God, through Paul, describes homosexual acts as unnatural. I believe he does so because God created our bodies and gave them particular purposes. One of those was for sexual pleasure between a nan and a woman, as well as for creating of children. For this reason it is unnatural for a man to have sex with an animal and for a woman to have sex with a woman. God calls these activities unnatural and shameful. He calls homosexuality "perverse." (Romans 1:27) If God says so, then I, as a Christian accept this conclusion.
I do not expect a person who has not submitted their life to God to accept the biblical definition of what is natural. However, I believe I have full right to do so, and this is one of the reasons I consider homosexual intercourse to be unnatural in addition to the physiological and health reasons. It seems that your standard of what is natural is what animals do ( I want to be cautious and not put words in your mouth, but this appears to be your argument. Please correct me if I am wrong here.). I understand that this is a possible definition and believe that one can be consistent in using such a definition. By this definition, cannibalism, incest, rape and murder are "natural." I do not accept this conclusion. I include homosexual relations in my personal definition of "unnatural" for the reasons listed above.