1 Corinthians 5:1
It is actually reported that there is sexual immorality among you, and such sexual immorality as is not even named among the Gentiles—that a man has his father’s wife!

I scratched my head over this scripture when I first read it many, many years ago.
Many other translations soften the blow by saying stepmother instead of father’s wife.
However, there is no soft side to sin.
Watch some of those true crime shows or a forensics program and you quickly get a view into the unashamed depravity of people.
Better yet, Google the atrocities of Nazi Germany and look at some of the photographs. It is hard to believe people could inflict such pain on others but there is it.
Child pornography, sex slaves, masochism, sadism, prostitution – all show the sexual sinfulness of humanity. And all these things exist today!
So it is not unbelievable that a man would have sex with his own mother.
Perhaps this is why Paul said this immorality is not even named among the Gentiles.
There are all kinds of sexual immorality today and someone might say what they do is not as bad as what someone else does.
Sin of one person is never justified by the sin of another.
God does not compare sin to sin; but sin to the righteousness of Jesus Christ.