I think the verse refers to the fact that Adam and Eve set the pattern that all men and women were to emulate in the future. The verse isn’t referring to a non existent mom and dad of Adam and Eve(unless some one wants to try to posit the leaving of the garden as that of leaving the parents...I “ain’t going there) per se. They were the first couple joined together to be “one flesh” and after that all future couples would follow that pattern. The important part of that verse wasn’t the leaving of the parents per se;(though one would hope the couple would leave and not try to move in and take the son’s smelly socks with him and her various skin creams with her)...it was the leaving for the sake becoming one flesh with your spouse. As Adam was one flesh with Eve, so it was expected that all future marriage mind males become one flesh with their wives. That’s all....the colloquial custom Moses speaks of that the Hebrews practiced; was that an offspring leaves and forms his own family separate from the direct influence of his parents. Other cultures due to tradition or poverty may have couples and parents living in fair close proximity to one another if not with each other for periods of time. The verse speaks of men entering a close relationship with a woman while beginning to distance themselves from the parental /child love and protective bonds and their subjection to their parents’ authority. In that sense do they “leave” their parents!
Any attempts to equate such “leaving of parents” with Adam and Eve’s expulsion from the garden would be a misdirection of the verse’s meaning. God never intended men and women to fall out of fellowship with him. He never intended that men should “leave the garden” but to grow and mature as a species under his guidance, to fully self actualize as a race living as matter and spirit.
A man can’t be united in a way that a man needs to be with someone; that is, with his parents. The parents are a completed “one flesh”(”three’s a crowd”)...a man needs a woman so that he can be a completed “one flesh” with his own wife. THAT is the reason WHY..”a man leaves his parents and is united with his wife, and they become one flesh.
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“Couples and parents living in fair close proximity to one another” is a product of living in “walled cities” mostly.
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Rev 13:8 And all that dwell upon the earth shall worship him, whose names are not written in the book of life of the Lamb slain from the foundation of the world.From the beginning God intended that Christ would go to the cross. He knew what Adam would do. How do we understand the mystery of iniquity? The desire to sin is sin.
Gen 3:6 And when the woman saw that the tree was good for food, and that it was pleasant to the eyes, and a tree to be desired to make one wise, she took of the fruit thereof, and did eat, and gave also unto her husband with her; and he did eat.Here Eve reveals the condition of her heart. Note that Eves nature came from Adam before they ate the fruit and their eyes were opened. In Adam all die even Eve. If you want to predict Gods intent, look first at what happened and not what you think should have happened