Yeah, and for many years they had the full blessing of the church. What's your point?
History has shown that when the atheism of communist and socialist regimes grows strong, it has little regard for human life.
The governments of Stalin, Mao, and Hitler might have been so-called "atheist", but they were hardly secular. Hitler was raised a Catholic, never renounced his faith, and was never excommunicated. These evil empires borrowed many of the cult of personality and faith-based worship tenets of relgion. To say that secularists who don't worship a divine deity are destined to be Nazis is insulting, and shows that you don't have a leg to stand on.
Show me a society based on the secularism of Jefferson, Einstein, and Spinoza that has slouched into murder, genocide, and oppression.
You can't because there isn't one.