While I support you main premise, that morality is not dependent on belief in God or a religion. Your contention that morality is intrinsic in humans is incomplete. Humans have the capacity for good and evil. Very many humans commit innumerable immoral acts. Are humans more good than bad?
I think that religions were established to encourage socially positive behavior and discourage socially negative behavior as well as to establish a codified social order often hierarchical.
If humans were so good, there would have been little need for religion.
I have a hard time believing that everyone's conscience is the same as mine.