Would Adam and Eve have lived forever if they had not sinned? The answer is ‘yes’, but we must be careful with the logic.

We know that when Adam and Eve fell by eating off the forbidden tree, death was twofold – both spiritual and physical. 

Genesis 2:17 but of the tree of the knowledge of good and evil you shall not eat, for in the day that you eat of it you shall surely die. {Hebrew: dying you will die}"

Spiritual death was immediate and then physical death followed. The Bible teaches that Adam lived 930 years in total before he physically died.

Genesis 5:5 So all the days that Adam lived were nine hundred and thirty years; and he died.

This two-fold death resulting from the disobedience of Adam and Eve was devastating and catastrophic. Humanity would now experience decay, corruption and ultimately physical death (mortality). But more significantly Adam’s spiritual death meant that all those born of Adam and Eve would be spiritually dead from conception and be required to be spiritually ‘born again’ to attain back to spiritual life. [It is likely that children below the age of accountability have a special dispensation regarding judgement.]

John 3:6-7 That which is born of the flesh is flesh, and that which is born of the Spirit is spirit. 7. Do not marvel that I said to you, 'You must be born again.'

This link between sin and death is confirmed in Romans:

Romans 6:23 For the wages of sin is death, but the gift of God is eternal life in Christ Jesus our Lord.

It seems a reasonable deduction from this truth that if Adam and Eve had not sinned, they would have physically lived forever. Likewise, with Jesus. He did not sin (Hebrews 4:15) and was born spiritually alive because He was separated from the Adamic line of spiritual death – being conceived by the Holy Spirit (Matthew 1:18). It follows, therefore, that Jesus also, would have physically lived for ever if He had not voluntarily laid down His life. 

However, there is another biblical consideration. Consider God’s perfect design before the fall – God’s perfect pattern in the Garden of Eden. There was not just one tree, but two!

Genesis 2:9 And out of the ground the Lord God made every tree grow that is pleasant to the sight and good for food. The tree of life was also in the midst of the garden, and the tree of the knowledge of good and evil.

In other words, in his pre-fallen state, Adam had a dependency on a life-giving source – the Tree of Life. In Eden, Adam and Eve could receive ‘life’ by just picking fruit off the Tree of Life – no sacrifice needed, no blood to be shed – just eat the fruit and receive the benefits of life everlasting. Eating off this tree was perhaps not a ‘one-off’, rather from time to time as required. 

Post fall, the source of life changed. Sacrifice was required to pay the price of sin and the life-giving source became a belief in the sacrificed Son of God (Jesus).

So, physical death was a consequence of sin (Romans 6:23), but eternal life (pre-fall) was not just dependent on a sinless life, but, by God’s perfect design (in pre-fall Eden), eternal life was also dependent on consuming the fruit from the Tree of Life! 

Biblically, eternal life has always been dependent on a divine life source. This life-giving source changed at the fall (of humanity) from the ‘Tree of Life’ to belief in God’s sacrificed Son.

Based on our initial logical link between sin and death, the question of whether Jesus would have lived forever if He had not laid down His life, was ‘yes’. However, this overlooked God’s original design in the Garden of Eden of the divinely placed life-giving source of the Tree of Life.

Of course, this question of ‘whether Jesus would have lived forever if He had not laid down His life’ is moot because Jesus was God! He had life in Himself!

John 1:4 In Him was life, and the life was the light of men.

John 5:26 For as the Father has life in Himself, so He has granted the Son to have life in Himself.

If He had not voluntarily laid down His own life, His physical and spiritual life, by definition, was self-sustaining. No ‘Tree of Life’ required. 

For the rest of humanity, however, the pre-fall Adamic human condition was immortal, but dependent on the life-giving source of the ‘Tree of Life’ in Eden. Post fall and for a time (6000 Bible Years), fallen humanity became incompatible with access to the Tree of Life.

Genesis 3:22-24 Then the Lord God said, “Behold, the man has become like one of Us, to know good and evil. And now, lest he put out his hand and take also of the tree of life, and eat, and live forever” – 23 therefore the Lord God sent him out of the garden of Eden to till the ground from which he was taken. 24 So He drove out the man; and He placed cherubim at the east of the garden of Eden, and a flaming sword which turned every way, to guard the way to the tree of life.

God in His wisdom angelically set ‘Eden’ off limits. Post Noah’s Flood, the geographical location of Eden became unknown.

By necessity, the Tree of Life will soon reappear in the Millennial Kingdom when access to the Tree of Life in Jerusalem will again be granted to those believers who, still being in their (non-resurrection) physical bodies will be required to eat its fruit for physical mortal longevity. 

Revelation 22:2 In the middle of its street, and on either side of the river, was the tree of life, which bore twelve fruits, each tree yielding its fruit every month. The leaves of the tree were for the healing of the nations.

In the Millennial Kingdom, all nations will be required to annually visit Jerusalem at the Feast of Tabernacles:

Zechariah 14:16 And it shall come to pass that everyone who is left of all the nations which came against Jerusalem shall go up from year to year to worship the King, the Lord of hosts, and to keep the Feast of Tabernacles.

No doubt, those rebellious nations who do not go up to Jerusalem at Tabernacles will by default not receive the fruit (off the Tree of Life) and that’s possibly why unbelievers will die at around 100 years old:

Isaiah 65:20 “No more shall an infant from there live but a few days, nor an old man who has not fulfilled his days; For the child shall die one hundred years old, But the sinner being one hundred years old shall be accursed.”

This is the wisdom of God.