Hmmm… nice troll.
Maybe the Roman Emperor Constatine. I’d like to try and persuade him out of using the guise of Christianity to further his own agenda of power, thereby creating over a thousand years of persecution against heretics (Jews). That decision to popularize Christianity empowered the Catholi Church, thereby leading to all sorts of atrocities against Jews over the centuries. Doubt he would listen though. Wonder if 10 words would do it….