Religion have defined morally what is right and what is wrong since thousands of year,like one must not kill ,not steal,not lie etc. It has defined the laws and had made it clear that their are rewards in this life and the afterlife too who follow these laws, and punishment for those who don't. Without religion, people in dark and medival ages would have thought " if a honest, tax paying,hard working farmer will end up the same as a murderer, thief or a criminal, then why should I be a honest guy?". As if you say there is no good,it means there is no evil..and if there is no good and evil then there is no hell or heaven or karma who you will be facing for your sins.
Modern athiests can say you don't need religion to say what's wrong and what's right but that is because religion had defined what is right and what is wrong and it has became a default morality which even the athiests follow.
Modern humans are not like people in medical or dark ages and they will turn towards athiesm, and in the process, millions will became narcissistic and will think what is their purpose here..then will come a turning point of humanity, the next evolution of human philosophy, the next breed of humans..the humans Friedrich Nietzsche defined as ubermensch or Superman or overman.