Everyone in the world was a mass murderer back then and this continues even today.
Therefore, it was not our affirmation that Christ is the only path to salvation that caused mass murders.
Christians were persecuted and killed by the Romans for centuries before the Empire became Christian. Our martyrs never incited violence, yet they never submitted or denied the Faith — something you want us to do.
Our fallen human nature is evil, not Christianity. It was Christianity that ended mass murders, human sacrifices, ritual assassinations, rapes, and slavery in the Christian world. These horrors continue only in places that have not accepted Christ. Other religions did not stop them.
With this statement, it is clear to me that you are not Catholic. This is pure progressivist propaganda designed to demonize Christianity.