The same way a married person justifies an affair, or a thief justifies embezzling or anything anyone does wrong and they know in their heart it’s wrong.
Bingo
Agreed. Not just affair, IMO. Take sex outside marriage, for instance, which seems to be an increasingly accepted behavior nowadays. Even if we don't do it, I wonder how many of us can easily accept our brothers/sisters/neighbors who date and without doubt are having sex with their girlfriend/boyfriend outside marriage. Or to covet our neighbor's wife (modern version of it: drool over Cathrine Zeta-Jones whenever Maureen Dowd's article is posted), something that is mentioned in the Ten Commandment. Isn't such action also condemned by the Bible? Yet, we make light of it, and consider it normal. But any mention of homosexuality, even when the person who confesses his/her struggle as a gay Christian, we tend to condemn them as unforgiven sinner.