When did Adam die spiritually? I will contend that Adam died spiritually before he ate fruit from the tree of the knowledge of good and evil. In other words, eating the fruit was “the fruit” of his already perceived separation from God.
Remember, Adam ate from the tree thinking he could become like God forgetting that he was already made in the image and likeness of God. He attempted to become something that he already was. He didn’t have to become like God because God made him who he was. Just as God says “I Am Who I Am”, Adam simply was who he was because God made him that way, perfect. There was nothing Adam could do to add to his image.
When Adam ate that forbidden fruit, he was essentially acting upon what he already wrongly believed was true about himself; that he needed to be like God.
Jesus said “You have heard that it was said to those of old, ‘You shall not commit adultery.’ But I say to you that whoever looks at a woman to lust for her has already committed adultery with her in his heart.” Matthew 5:27-28
He was saying to those who trusted in the law, that they have learned that breaking the law meant to act upon their lust when in reality they broke it when they entertained even the thought of it.
In the same manner God commanded Adam not to eat from that tree because he would surely die, but Jesus’ teaching shows that it wasn’t the act of eating that caused his separation from God but the very idea and false belief that he was separated in the first place, and THAT was when he died.
To “know” your wife biblically is to become one with her. Eternal life is to be ONE with God. Jesus put it this way, “And this is eternal life, that they may know (be one with) You, the only true God, and Jesus Christ whom You have sent.” John 17:3. You have been made ONE with God. Any attempt or belief to become something the Father has already made you is spiritual death. All we can do be a reflection of what God has already made us.