(1) Adultery is not your average indiscretion. Breaking a marriage contract is illegal in most jurisdictions (though it is rarely enforced).

(2) When you teach at a religious institution, "personal life choices that don't affect their work?" is less of a thing, because you've deliberately related work and religion (i.e. personal choices).

It might not be your cup of tea, but some students want to attend an institution of high moral standards, as well as high academic standards.