I have seen many different believers in my life, both those who act with reason and those who act with their hearts... it's all very multifaceted. I have also seen militant atheists in my life during the Soviet era. They also acted based on their faith in the communist future of humanity (either through reason or through their hearts), and they considered religion to be a delusion, just as believers consider atheism to be a delusion. Everything is essentially the same in this world. The only difference is the objects of worship.
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"So much has gone
and little is new"
David Bowie