It seems to me that this discussion has gotten of the expressed topic. I will address the new topic and then the original.
For me morality is based on rules and regulations, while sin is based on relationship. That means that the OT is based primarily on morality, the Decalogue, etc., while the NT is based on relationship, Love God and Love others as yourself.
One can be sinful, while being moral, that is obeying the letter of the law, as Jesus and Paul pointed out.
In terms of evolution and morality the best application that I have seen is to say that old natural man, has evolved based on survival of the fittest is governed by the selfish gene. Evolved selfish persons must be born again of the Spirit so they can be free of sin.
Evolution has little to do directly with a platonic dualistic anthropology. Plato’s anthropology was originally tripartite, body, mind, and spirit. Only later I think under the influence of Socrates did it become dualistic. The Greeks generally believed that the body was inferior to the spirit. Jews and Christians do not.
Despite our heritage of mind/body dualism, we do have a tripartite understanding of humans, id, ego, and super ego. Id represents the physical person, ego represents the rational person and super ego represents the moral person. Psychology was seen as a struggle between the id and the super ego for control of the ego. Freud sought to integrate these three, usually advising to suppress the superego to get rid of guilt and sin.
Evolution does not encourage selfishness. Selfishness leads to failure and extinction. Cooperation leads to survival and flourishing. Survival of the fittest as taught by Darwin, Dawkins, & Co is wrong. Symbiosis as taught by ecology is right.
Sin for Christianity is selfishness. Putting yourself first, others next, and God last. In a sense babies are born selfish. A newborns only need is to survive which means it must have its needs met by others. It is only later that they learn to share and be considerate of others, but of course many never really learn.
The problem is how to move from self, others, God to God, others and self. One cannot put God first for selfish reasons. Repenting and being born again means to give up your own way and seek God’s way first and foremost
On the other hand God’s way is not against you, but for everyone. God’s way unites love for God, others, and self. God’s way also unites body, mind, and spirit. Love YHWH with all your heart, mind, soul, and strength.