Perhaps we can be forgiven for remaining blithely ignorant of just how depraved societies that abandon true faith can become. Until today, I did not know that incest between consenting adults is legal in China, France, Israel, the Ivory Coast, the Netherlands, Russia, Spain and Turkey. In Spain the age of consent is 13.

In Switzerland, where consensual incest between “second-degree” relatives like aunts and nephews or between cousins is already legal, the Upper House of Parliament recently proposed a law decriminalizing consensual sex between “first-degree” relatives (e.g., between fathers and daughters or between siblings). The age of consent in Switzerland is 16.

Columbia University political science Professor David Epstein probably wishes he lived in one of those countries: He was just arrested and charged with having a three-year consensual sexual relationship with his 24-year-old daughter.

The question is not whether a movement to legalize incest between consenting adults is coming to America; the question is simply when. Incestuous relations between consenting adults is no more depraved and perverse than sexual relations between two men or two women, which we now celebrate in our streets and our public schools.

Oh, and don’t forget, accompanying this effort to normalize yet another manifestation of sin will be a fight to lower the age of consent.

And when it arrives, we will be left devoid of justifications for opposing it because all the same reasons used to normalize homosexuality will be used to normalize adult consensual incest:

• Who are you to impose your personal or religious beliefs on others?
• Opposition to adult consensual incest is motivated by puritanical provincialism and prejudice.
• What goes on between closed doors is no one’s business but the two (or more) people involved.
• All that really matters is that those involved love each other.
• How does the incestuous relationship of Mr. Brown and his daughter Susie affect your relationship?
• It is unjust to deny any adults the freedom to love whomever they please.

The central reason offered to prohibit incestuous relations is that their offspring are at increased risk for genetic disorders. But this is not a compelling moral reason to oppose consensual incest.

First, not all children born to close relatives suffer from genetic disorders. Second, laws permitting incestuous marriages between “first-degree” relatives could include a provision requiring genetic screening.

If the only reason for prohibiting fathers from being in sexual relationships with daughters is the increased possibility of passing on a genetic disorder, then why do we permit marriages between Jews who may pass on Tay-Sachs disease or blacks who may pass on sickle cell anemia?

The reason that we don’t prohibit Jews from marrying Jews or blacks from marrying blacks despite the increased risk of passing on genetic disorders is that these types of relationships are not inherently morally flawed whereas incestuous relationships between fathers and daughters are.

Furthermore, if the possibility of passing on genetic disorders is the only reason for opposing legalized consensual incest, then what possible reason is there to oppose a father being in a sexual relationship with his adult son?

If fathers can be in sexual relationships with their daughters or sons, and if marriage — as a public, government-sanctioned institution — is severed from gender and procreation, will fathers be able to marry their adult sons?

How will the legalization of consensual incest affect family life? How will the weakening or eradication of the incest taboo affect how mothers and fathers physically interact with their children or teens?

Will the loss of the incest taboo diminish trust within families? Will it make parents apprehensive about interacting affectionately with their children? Will it make parents suspicious of the nature of their marital partner’s affectionate interactions with their children?

And are these concerns compelling enough to defeat the next phase of moral corrosion in a society in which so many have rejected the idea of all moral absolutes except one: absolute liberty?

As Neil Postman warned, we no longer think; we feel. So, all we need is a big Hollywood tearjerker about a star-crossed brother and sister who because of society’s bigotry are prevented from openly expressing their love and from accessing the benefits and social validation that come with marriage, and the incest taboo will fall.

We need to heed the portentous words of Professor Epstein’s attorney Matthew Galluzzo who said that “there is an argument to be made in the Swiss case to let go what goes on privately in bedrooms. It’s OK for homosexuals to do whatever they want in their own home … How is this so different? We have to figure out why some behavior is tolerated and some is not.”

I hope and pray that the church — that is to say, church leaders and the people they lead — will do a far better job opposing this and all other forms of sexual perversity than they have done so far.