Our hope of eternal life is secured. Heaven is secured by Christ, whom Paul calls the last Adam (1Cor 15:24). By His obedience and sacrifice, Christ has secured eternal life and the heavenly rest that Adam failed to secure. This is good news for all who rest their faith on Him.
I think one of the hardest sells for us Christians to make to unbelieving world is the fall of all mankind in Adam as our representative. Why, over simply eating a fruit from a tree was there such a fall, such a curse?
I actually agree that if it was just a simple touching of a tree or a little bite of fruit, it seems excessive. But if we look at the biblical text it was far more than that. It was a complete betrayal of God, and an agreement with the deceiving enemy. It was a failure to do what he should do and a taking and doing what he should not do.
To understand the scope of the sin we need look no further than the biblical text itself, but not just at the text of the event itself, but the greater context of the environment, situation and duty Adam had in the garden that shows this was much more than an issue of intemperance. Which is exactly the point that John Calvin makes:
We must, therefore, look deeper than sensual intemperance. The prohibition to touch the Tree of Knowledge of good and evil was a trial of obedience (obedientiae examen), that Adam, by observing it, might prove his willing submission to the command of God (Institutes,2.1.4)
Calvin points out that Adam’s situation was that he was undergoing a “trial”. It was a “trial of obedience”. We know that in Romans 5, Paul tells us that Adam was a type of the one to come (Christ) -Romans 5:14.
We can understand a lot more about how this was a trial by looking at a the testing that Jesus went through in the wilderness in Matthew 4. Immediately at the start of Jesus ministry he is led by the Spirit into the wilderness to be tempted by the devil. How this parallels with Adams’ temptation is not a coincidence, but this is actually at the heart of Christ’s mission on earth. Christ is the promised Seed of the woman, and this battle with Satan is exactly what Christ came to succeed at where Adam failed.
We may note that Christ came into a fallen world, into a harsh wilderness instead of a safe garden, and with intense suffering and hunger instead of a full stomach. He endures, he succeeds, and does what Adam should have done. He faced the tempter three times! Each time, Christ obeyed God. Instead of agreeing with the tempter, Christ vindicated God, and sent the serpent way! This is what Adam should have done.
If we look earlier in Genesis we see that in Genesis 1:27-30 that God made Adam in His own image, and gave him dominion over everything. Adam was God’s great creation, created above the rest of the creation on earth and given dominion over it. He had a job to do.
God also put the Tree of Life in the garden along with establishing the Sabbath rest. These are signs relating to eternal life, a rest or competition of the probationary trial and entry into consummation.
We see the environment of the trial of obedience starting with Genesis 2:15, which most of our English translations don’t do a good job of translating the word “keep it” in relation to the garden.
The Hebrew word “shamar” there is actually better translated to “guard”. It’s used that way in Genesis 3:24 describing the action of the cherubim with the flaming sword that turned every way to “shamar” (guard) the way to the tree of life. Adam should have guarded the garden from the invading serpent.