And what do you think communism is based on?
The worst regimes of the 20th century have been atheistic, which is not much different than humanism.
It’s not the political system that’s the problem, it’s the belief system. Humanism/atheism answers to no one but themselves. Anything goes and anything can be justified because there are no outside moral constraints; only those imposed by those in power.
Islamists justify their inhumane actions by their "GOD" as did Christians in the past. Humanity, justice, morality does not flow only from a religious spring. That is why those in power have to be vetted to be moral within themselves prior to their rise to power.