Atheism is all about situational ethics (among other things). Oddly, they see many laws as “Christianity” that are really not. i.e. laws against murder or robbery, or anything protecting individual rights to make good or bad decisions or believe whatever you want.
Abortion, their flagship issue, is about whether you are ending a human life or not. And to be clear, most of them are for it even if it IS a human life being ended. That thinking leads to infanticide and, truth be told, even justifying killing an adult that is making your life “hawrd”.
Atheism is nothing more than narcissism with an uppity attitude.