I always thought that if one believed sexuality was wrong, then
refraining from sexual activity would be consistent with one's beliefs.
The way you phrased that, it sounds as if a man were tobelieve in the sanc y of marriage, then if he cheated on his wife, he would be consistent with his beliefs as long as he covered it up.
Anyway, it is not that this scandal undermines the argument against gay marriage. It is that it is eroding the moral authority of an existing political ins ution arguing against it. If the leader of an anti-abortion organization were discovered to be performing abortions left and right, it would devastate the credibility of that organization.