So The Bible in The Book of Genesis describes that Adam and Eve were created as immortal,But this immortal is not equal to the Godly immortal as its tied to a law, if Adam and Eve break the law of God then they lose all rights to access this immortality. Proof that Adam and Eve were immortal prior to the fall.
but you must not eat from the tree of the knowledge of good and evil, for when you eat from it you will certainly die
The verse above means that as long as Adam and Eve avoided the tree of knowledge of good and evil, the were never going to die.
It can also be noted that this immortality needs the Tree of Life for perpetuation. God seals access to the Tree of Life to prevent Adam and Eve from eating of it to leave forever as sinners. Check out the verse below for more details.
And the LORD God said, “The man has now become like one of us, knowing good and evil. He must not be allowed to reach out his hand and take also from the tree of life and eat, and live forever.
In order to protect the tree above then a flaming sword that turns in all directions was placed at the East of the garden after Adam and Eve are sent out. It could also be that the devil was jealous of Adam's and Eve immortality and lied to them so that they would lose it.
But also this was part of the plan as Abraham sacrificing Isaac was a foreshadowing of God sacrificing the Christ for the sins of the whole world.
So did Jesus come to restore the immortality that Adam and Eve lost? Is this immortality the same as that the enjoyed in the garden? Will Jesus allow the saints to eat from the tree of life?