God had to remove them from the Garden to prevent them from eating from the Tree of Life and thereby living forever
I used to ask this same question and similar ones as a kid.
Why did God keep the tree of life around and have to post Cherubs with revolving swords at the entrance of the garden if his plan was to have Jesus die for mankind to gain everlastion life again ?
If there was an entrance to the garden, what if Adam and Eve simply went a few miles down the road and snuck in and ate of the tree when God wasn't looking like he wasn't looking when they ate the forbidden fruit ? It seems like God was afraid that if they accomplished that, he would be powerless against them. He wouldn't be able to take everlasting life back once they had it and therfore would have nothing to hold over them.Would he still be almighty?
How come there had to be a tree of life if they were already perfect and were meant to live forever?
The fact is, if you beleive any of this stuff is literal, then it's easy to convince yourself that god will do a whole bunch of other stuff to make it all work out the way you want it to. The extent of what he might do is directly proportionate to the limits of your own imagination. All people know the same truth, our lives direction is determined by how we choose to distort it.