Damnatio Memoriae

Damnatio memoriae is the Latin phrase literally meaning "condemnation of memory" in the sense of a judgment that a person must not be remembered. It was a form of dishonor that could be passed by the Roman Senate upon traitors or others who brought discredit to the Roman State. The result is to erase someone from history.

The sense of the expression damnatio memoriae and of the sanction is to cancel every trace of the person from the life of Rome, as if he had never existed, in order to preserve the honour of the city; in a city that stressed the social appearance, respectability and the pride of being a true Roman as a fundamental requirement of the citizen, it was perhaps the most severe punishment.

It's the idea that all the good you may have thought a person expressed in the past now must be rejected because of the bad you think they've recently embraced. Those who have previously appreciated the contribution of the now-exiled person are instructed to avoid any further reference to that person or his past contributions.

A sad thing, but just the way arrogant religionists, uh, I mean, egotistical Roman leaders were.