One of the techniques used to prove homosexuality is sinful behavior is the equation of biological naturalness with spiritual morality. Let me illustrate an example.
We assume human beings are naturally inclined, in a biological and evolutionary sense, to seek out and mate with the opposite sex in order to create offspring. As such, because biology and evolution dictates that the propagation of Homo sapiens be predicated upon mating with the opposite sex to produce offspring, we equate heterosexual behavior as the normative form of sexual attraction which is therefore accepted as morally normative as well.
Homosexuality, because it does not follow the biological normative of heterosexual behavior, since two members of the same sex cannot produce offspring, and is not part of the natural trajectory of human development / evolution, it is likewise considered as morally unacceptable or sinful.
If we accept this argument then we must accept other inconvenient truths as well. According to this argument, we should not complain about absentee fathers or sexual promiscuity. Biology and evolution also dictates that males abandon their young and seek out multiple sexual mates to propagate their species. The role of males, at least in a natural, biological sense is not to be fathers but to spread their genetic traits to other females, who will then transfer those traits to their offspring. Likewise, females are to accept multiple sexual partners in order to give birth to strong, healthy offspring.
So in this sense, men should not have to accept the responsibility of fatherhood nor should they, as well as women, engage in monogamous sexual relationships because it slows the spread of valuable genetic material. Are we willing to accept this behavior as right because nature, biology, and evolution makes it normative? You be the judge.
Biology, nature, and evolution also dictates war, disease, and genocide as natural methods of population control. Among insects for instance, scarce resources or a crowded habitat often leads those insects to cannibalize each other in order to reduce their population to a sustainable level. Disease serves the same purpose. Eliminate a large number of the population in a short amount of time to reduce the stress placed on resources so that the species can persist.
Insects, at least in a macro sense, are very much like human beings. We exist in large numbers, find ourselves competing for natural resources, and often live in very close proximity to one another. But every few centuries, the human population reaches levels which are quite simply non-sustainable. This is when war, disease, and genocide come into play.
By killing one another, we eliminate excess users of our natural resources, allowing those resources to replenish, only to be reaped by humans who survive the spate of violence. We also create a comfortable distance amongst ourselves to prevent the spread of disease and to utilize our fair share of resources without placing an undue burden on our fellow human beings.
We should not try to prevent these evils because it’s nature’s tough love, or her way of making sure we do not go extinct. They are unavoidable necessary evils that are hardwired into our genetic make-up. It is our evolutionary, primal urge to destroy potential competitors as a means of ensuring our unconscious collective survival. Again, are we to accept these inconvenient truths as morally acceptable? Are we to consider them right because it’s merely natural? Once more, I ask you all to decide.
To put it simply, we should never accept that just because something is natural that it is automatically right. If we truly thought that way about everything then I am certain our world would be a much darker place. Walking down the path of equating biological normativeness to morally acceptable behavior is a very dark journey. It is the same mode of thinking that dictated the eugenic policies of the Nazis and other sorts of genocidal orgies which have haunted humanity for centuries. If we accept it, than we are lending ourselves to morally degrading behaviors that have a capacity to destroy that very thing which makes us human; our sense of soul.