Regret in Heaven?

I'm gonna have to go with Phil Gons over John Piper on the issue of regret in heaven.  Discussing the second chapter of Piper's book Life as a Vapor, Gons says:

Piper reasons that since we will spend eternity praising Christ for ransoming us (e.g., Rev 5:9), we’ll certainly remember our sinful condition from which we’ve been ransomed. And those memories will yield feelings of regret.

It is inconceivable to me that we will remember our sin for what it really was, and the suffering of Christ for what it really was, and not feel regretful joy. . . . It does mean that regret will not ruin heaven. There will be kinds of joys, and complexities of happiness, and combinations of emotions in heaven of which we have never dreamed. (20)

Piper feels some tension leading him to speak in terms of “regretful joy.” He addresses Revelation 21:4, but concludes that he doesn’t think that it “rules out tears of joy” or “regretful joy.”

With all proper deference to John Piper, who is one of the great saints of our age, I have to agree with Phil when he says:

I’m having trouble being convinced. Regret is defined as “a feeling of sorrow, repentance, or disappointment” (Concise OED), “a sense of repentance, guilt, or sorrow, as over some wrong done or an unfulfilled ambition” or “a sense of loss or grief” (Collins English Dictionary), and “sorrow aroused by circumstances beyond one’s control or power to repair” or “an expression of distressing emotion (as sorrow or disappointment)” (Merriam-Webster’s).

Revelation 21:4 speaks of the permanent removal of mourning (πένθος), crying (κραυγὴ), and pain (πόνος). BDAG defines πένθος as “sorrow as experience or expression, grief, sadness, mourning” (795), κραυγὴ as  “outcry in grief or anxiety, wailing, crying” (565), and πόνος as “experience of great trouble, pain, distress, affliction” (852). It’s clear from a passage like Isaiah 65:14 that πόνος can refer to emotional pain (πόνον τῆς καρδίας) as well.

I struggle to see how the elimination of these leaves room for genuine regret (i.e., sorrow, disappointment, grief, guilt, distress). But since Piper never defines regret or “joyful regret,” it’s hard for me to know exactly what he has in mind. I’m really having a difficult time getting my mind around the concept of “joyful regret.” And if our praise of Christ for His work of ransoming us will be unceasing, and that praise requires that we remember our sin, then it would seem that our regret would be as constant as our praise.

Is it even right for believers to feel regret when recalling past sin?

I think one of the determinative passages on this is Jeremiah 31:34:

“People will no longer need to teach their neighbors and relatives to know me. For all of them, from the least important to the most important, will know me,” says the Lord. “For I will forgive their sin and will no longer call to mind the wrong they have done.”

If regret involves remembrance of past sin, and if God commits to not remembering our past sin, then how can we remember (regretfully) our past sin?

That last question that I quoted by Gons is one that I have given some thought to - aside from and before the question of regret for sin in the eternal state, should believers even feel regret for past sin while on this earth?

I will say that I am surprised at the determination of many I meet to live with a sense of guilt.  I meet many Christians who are fully committed (or as my friend Glenn Lucke says, they are "all in") to hanging on to guilt.  No amount of teaching or persuasion regarding the merits of Christ's work can convince them that they are free from guilt.  True, they may accept and be thankful that they are free from legal guilt, but experiential guilt is something they believe they must hang on to.

John MacArthur once said that the process of sanctification is the process of making our practice match our position.  In other words, we are positionally righteous before God, so we ought to make it our ambition to be practically righteous.  We understand that, because of indwelling sin, we won't do it perfectly in this life, but we still seek it.

Doesn't the same go for guilt?  We are positionally free from guilt because of the work of Christ.  Shouldn't we treat "experiential guilt" as an enemy the same as the other things for which the death of Christ paid the penalty?