Atheists and secular humanists quite obviously argue that we humans are all alone and that humans themselves determine their worth, their value, their ‘intrinsic’ dignity. The problems with this ought to be self-evident but atheists are crafty folks. History reveals clearly that humans can change their minds about the ‘worth,’ ‘value,’ and ‘rights’ of humans (usually other humans). For example, the Nazis depersonalized the Jews with consequences I need not expand on. Atheistic communist regimes depersonalized dissidents and capitalists with consequences I need not expand on. The atheistic apologetic on the point is that actually this goes to show the dangers of ‘religion.’ For, you see, anyone who ever does anything nasty, no matter what their ideology, is, by definition, acting religiously. In this way, atheists can always keep their hands clean.
However, it misses the point. The fundamental point has to do with our basis for decrying what the Nazis and communists did. If humans themselves are the sole and final arbiters for determining and dictating human value then no one can complain about what humans decide. Oh sure, the do complain. But in doing so they betray the inconsistency of their position.