Once and a while I would bring up this issue in church classes. I got a couple of decent explanations, but nothing that definitively put the issue to rest. That all changed last Sunday in gospel doctrine class.
During our classroom discussion on the Fall, someone raised her hand and asked the ubiquitous question: Why were Adam and Eve forbidden to eat the fruit if it was supposed to happen? The teacher dutifully pointed out that it was not a sin, but a transgression. Yet like so many times before, my mild confusion persisted and I consigned myself to the fact that I will never know the answer in this life.
Then something significant happened.
The teacher went on to explain President Brigham Young’s teaching on the earth moving away from the presence of God after the Fall. I knew about this teaching, but when she said it, a thought came to my mind. The thought was this: The Lord forbade Adam and Eve from taking the fruit because mortal beings cannot exist in His presence. In other words, when Adam and Eve ate the fruit, it started the process of transforming their bodies into a mortal state and mortal beings are forbidden from being in the Lord’s presence. Thus forbidden refers more to the consequences of eating the fruit than to the act itself. For Adam and Eve to be in that heavenly sphere whilst being mortal was a transgression. Hence the earth was sent to a lower, telestial sphere appropriate for mortal beings.
It might help to think of it this way. Adam did not transgress a moral directive from the Lord. He transgressed a law of Heaven which states that mortal beings cannot be in His presence. This concept is consistent with the teaching that mortals who see God must undergo a physical change to withstand His presence. Such was the case with Moses and Joseph Smith.
I am grateful that I finally have my answer to this question.