How Could We Not Sin in Heaven?

I've often wondered how God will bring it about that we will not sin in heaven. If God can bring it about that we not sin and yet retain our free will, then why did He not make it that way from the beginning? I think I've hit upon a partial solution, or perhaps a complete one. But first it is important to note that there is a distinction to make. In heaven, it will not simply be the case that we will not sin, but that we will be unable to sin. Does this crucial point mean that our choices will be somehow restricted, or even taken away altogether? How can we be free and obey God without the possibility of disobedience?

I would like to begin by making an analogy that will perhaps explain a bit of the situation. Each person, though all totally corrupted by sin (Romans 3), has differing desires for sin. I, for example, have no desire to indulge in drunkenness, though for others it is a serious temptation, and all have their own weaknesses. It could be the case that just as I have no desire to become drunk on my own, and that if anyone offered me the opportunity, I would reject it, in heaven this would be the case for all sins. Our inclinations would be such that if offered the chance to sin, we would freely reject it. But we can go even further. Only the righteous/saved will dwell with God in heaven (Revelation 21). Just as I will not only not choose drunkenness if it is offered to me, but will also not offer the choice to another (because of my own inclinations), no one in heaven will offer temptation to anyone else, because no one will be inclined at all toward any sin. So not only would we freely choose every time not to sin on our own, but the choice or temptation will never even be offered because no one will have sinful inclinations.

Does this capture the inability to sin, or is it simply a very strong form of the ability not to sin, which Christians (and only Christians) possess right now? I think that while the above may be helpful in imagining our state of mind in heaven, it does not quite capture our total inability to sin before God. Lenny Esposito points out (http://www.comereason.org/phil_qstn/phi039.asp) that God is unable to sin, though no one doubts He is totally free. Therefore it is indeed possible to be free and have an inability to sin. It could be that just as I (as a Christian not bound by my sin nature) am totally free (in the Sartrian sense of never being totally unfree), I do not have the ability to fly unaided. This does not essentially restrict my freedom (since we are not claiming a sort of radical freedom).

Granted, though, flying and making moral choices are not quite the same. For a complete understanding we must look to the Bible. 1 John 3:5-6, 9 state :

You know that He appeared in order to take away sins; and in Him there is no sin. No one who abides in Him sins; no one who sins has seen Him or knows Him. … No one who is born of God practices sin, because His seed abides in him; and he cannot sin, because he is born of God.

It is our partaking in the nature of God that provides us with the inability to sin, because God cannot go against His own nature, namely, absolute holiness. Esposito writes:

Because we have two natures that are at odds with each other, there is an inner struggle that exists in every believer. Romans 7 is dedicated to showing this struggle. However, upon death, the old man will pass away leaving only the new, divine nature. One of the most important passages to understanding this is found in Romans 6:4-7:

Therefore we have been buried with Him through baptism into death, so that as Christ was raised from the dead through the glory of the Father, so we too might walk in newness of life. For if we have become united with Him in the likeness of His death, certainly we shall also be in the likeness of His resurrection, knowing this, that our old self was crucified with Him, in order that our body of sin might be done away with, so that we would no longer be slaves to sin; for he who has died is freed from sin.

The last verse is key - "he who has died is free from sin." When we're saved and choose to be baptized, we die to ourselves and receive a new nature. This nature is in conflict with our old fleshly nature. When our bodies die, that old nature perishes completely as well, leaving the divine nature alone.

Now we return to one of the big questions I raised at the beginning: If God can bring it about that we not sin and yet retain our free will, then why did He not make it that way from the beginning? There is no easy answer to this question, and in the end we must trust God's wisdom. But Christian philosopher William Lane Craig writes that perhaps the only way heaven could exist would be as a result of our life on earth (http://www.origins.org/offices/billcraig/docs/craig-bradley0.html). He says:

Heaven may not be a possible world when you take it in isolation by itself. It may be that the only way in which God could actualize a heaven of free creatures all worshiping Him and not falling into sin would be by having, so to speak, this run-up to it, this advance life during which there is a veil of decision-making in which some people choose for God and some people against God. Otherwise you don't know that heaven is an actualizable world. You have no way of knowing that possibility.

There is also the very old concept of the felix culpa, or the happy fault. This idea, briefly stated, is that God allowed the Fall in order to bring about a greater good through the Incarnation of Christ and the salvation of our souls. As Aquinas writes in his Summa Theologica,

But there is no reason why human nature should not have been raised to something greater after sin. For God allows evils to happen in order to bring a greater good therefrom; hence it is written (Romans 5:20): "Where sin abounded, grace did more abound." Hence, too, in the blessing of the Paschal candle, we say: "O happy fault, that merited such and so great a Redeemer!" (http://www.newadvent.org/summa/4001.htm#3)

We see in the world that God allows some evil to occur in order to bring about a greater good, and so it can be inferred that if our relating to Christ in the way that we do now is the greatest and ultimate good, God might permit the entry of sin into the world in order to accomplish it.