Mankind has given up on God. They feel isolated.
I don’t think mankind has given up on a God so much as they have diminished Him. They have taken Him off His throne as absolute righteous Judge and omnipotent creator and turns Him into a kindly if not doddering old man who winks at their sin and just wants to be sure everyone has a good time. That is a greater sin than forgetting Him. God will not be mocked
Even as redeemed and dearly beloved children and heirs I think Christians forget just how powerful righteous just and holy our Father is.