The perennial debate about ethics and religion.
Step one Define ethics:. Standards of behavior that provide stability and cohesion to society
Step 2 define religion:....Reverence and rite directed to a numinous (mysterious and awe-inspiring) "other".
Step 3 explain why 1 cannot exist without 2 .... Some say without fear of supernatural punishment ethics cannot exist. Why? Is ethics the product of the avoidance of pain? If so then ethics are reduced to a most animal level and would not seem to require a numinous other to understand. Is ethics the product of the promise of reward? Then ethics are self serving and again would not seem to require a numinous other to understand. Some say ethics must be superhuman to be trustworthy. This then invites the question of how do we know an ethic is superhuman? The ethic must be able to be rationally defended as superhuman lest imposters feign superhuman. If therefore rational humans can determine the rationality of a superhuman ethic then do the humans need the superhuman? No.
In other words as soon as you admit you can defend the ethics as being rational and valuable you erase the need for a supernatural source. Humans are quite capable of exercising good judgement about ethics and value. The fact that they don't all agree on a given topic reflects the differences in perspective more than a difference in values. The abortion issue is a classic. For many the potential to become a human is equated with being a human. For others the potential to become a human is just that and something that the mother has the right to determine. There will always be some issues beyond consensus. Religion, or more accurately each religion, pretends to offer clarity but actually cannot be rationally argued when challenged. It is in these very areas of debate that religion fails to appear supernatural.