The term two faced refers to the Roman god Janus, who had two faces. It was assumed that a person who would say one thing to one person and a conflicting thing to another would have two faces, like Janus. All the Abrahamic religions are this way.

The modern term for two faced, is mask on, mask off. All the Abrahamic religions are this way. However, it does not describe people who work to undermine people in secret or people that jekyl and hyde. White people like to jekyl and hyde and sneak around behind people's back.

Another common is people who are paid to say and act a certain way, acting as their donors pay them to behave. They decieve your trust in them by not disclosing that they are paid shills. Shill, a person who publicly helps or gives credibility to a person or organization without disclosing that they have a close relationship with said person or organization, or have been paid to do so.