Here below is a republication of a long essay I wrote back in 2009 under the general title Apologia Pro Opere Sui. At the request of more than one reader, I have stripped out the specific comments related only to the event that provoked it, in order to frame the argument in more general terms.
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As a faithful Roman Catholic who was an atheist for all his adult life (and most of his childhood) I occupy an interesting position in the ongoing debates concerning the social turmoil caused by sexual unchastity, particularly that unchaste practice which issues forth from what is delicately called same-sex attraction.
One is tempted automatically to assume that atheists should support or ought to support the sexually liberated position that declares all sexual acts licit between two or more consenting adult partners in their right wits. One is tempted to assume that no rational grounds to condemn sexual libertinism exist, aside from the dogmas and supernatural reasoning of Christian theology.
This temptation must be resisted at all costs, since not only is it untrue, it is foolish, for the drives the conversation out of the realm of natural and logical reasons to avoid sexual immorality and into the realm of the supernatural and theological. Once the issue is falsely labeled as a theological one, is the falsely libeled as an issue where all discussion is offlimits for being a personal matter of irrational faith, then the topic is ejected forthwith from the public forum.
Allow me, then, to give a personal account of how it was that I, resting only on my human reason and with no particle of loyalty to or faith in any theological speculations (which, at the time, I frankly dismissed as egregious and base superstition), was drawn step by step against my will and very much against my inclinations away from the comfortable libertine and libertarian opinions of my youth to the conclusion that the sex act is licit only within marriage, that unchastity is illicit, and that unnatural sexual acts are illicit as well as unnatural.
There are perfectly natural and worldly reasons for a rational atheist to support the Christian position on sexual morality. The following argument shows that the Christian position is the only logical position to hold, given the realities of human nature.
One a personal level, I did not change my conclusions about sexual morality because I became a Christian. The cause and effect was the other way. After cold logic lead me to the conclusions that the only logical position to hold just so happened to be the one held by my (at that time) hated enemies the Christians, I began to look at their egregious and base superstition with a less hostile gaze.