What if the promise given to the church was more about human will and God accepting it?
If a human practice was morally unacceptable to God, God would have to accept the fact. Peter was even nudged into that direction by God telling him what was unclean to eat as food already was accepted by God in the vision of the unclean animals. Anything by extension, that is sin and condemned in the Law of Moses was open to change by the will of the new found church and body of Christ.
It could even be said that if the church embraced evolution then evolution would have been the means of God’s creation of all biological life. Is it just a means though of getting God to follow the whim of human’s demand for being the means of their own rightness? Or was it more a way of saying that God was placing trust back into humanity, after the failure of Adam and the defaulted Law of Moses?
Personally I think it was God saying I will give you thoughts, and when you carry them out in obedience then humsns will be in accord with God as one. I do not think that humans are capable of original thought. I think that their actions based on the thoughts they have in their mind determine an outcome. Even if this outcome is morally accepted by humanity, it may still be wrong in God’s will. Humans are capable of totally going against God and the thoughts given to us. That is free will. They can even believe that such disobedience to God’s will is inspired by God, to the point there is no dissonance of mind.