Many detractors of atheism like to point to the Holocaust as evidence of the immorality of atheists.
But the first Holocaust to ever take place in mainland Europe was the genocide of the Armenian Christian people by the Ottoman Turks.
This mass slaughter was observed by German onlookers who noted the use of cattle trucks to help make things easy, and was carried out by the Sultans and their Muslim warriors in the name of Islam.
One and a half million people died (in one estimate).
It’s hard to believe that something like this could go unnoticed by Christians.
Being a theist did not stop those men from killing and inspiring Hitler.