"Gutsy guilt" is a Piper term I learned in his book, When I Don't Desire God. He puts it like this in a sermon on Romans 8:1 (emphasis mine)...
The question is whether we will live the gospel. We must believe...finally and fully...that Christ really did all that was necessary to appease the wrath, displeasure, disappointment, despising of God. On our bad days when sin seems to reign over us we must hold firmly that God is not against us. When we have those rare good days when we seek Him, we must believe in our hearts that we've not added to the righteousness of Christ.
Now that is a picture of how to think and act when you sin against your Father whose whole disposition toward you is almighty mercy and omnipotent love. He will not always handle you gently. But he will always love you. And always be for you and not against you.
So we take our sins seriously. We hate them. We see them as a contradiction of who we are in Christ and a contradiction of our Father's love. We confess our sins (1 John 1:9). We look to the cross where all our pardon and righteousness was fully secured. We accept the Father's displeasure and discipline, and may dwell in darkness for a season. But if our enemy rejoices and says to us in our night of sorrow, "See, God is against you. He is angry. You are guilty and under his condemnation," then we will say, with the authority of Romans 8:1 and on the basis of Jesus Christ's death and righteousness, and in the words of Micah 7:
"Do not rejoice over me, O my enemy. Though I fall I will rise;
Though I dwell in darkness, the Lord is a light for me.
I will bear the indignation of the Lord
Because I have sinned against Him,
Until He pleads my case and executes justice for me.
He will bring me out to the light, And I will see His righteousness."
That is what I mean by gutsy guilt. I know of no other way to persevere in the Christian life in view of our constant failings - no other way to stay married for Christ's sake, to rear children, and be single and chaste, and maintain hope and fruitfulness in ministry, than this gutsy guilt: When I fall I will rise . . . though I have sinned, the very one against whom I have sinned will plead my case and execute justice for me - not against me, but FOR me! Oh, love this gospel, [Church]! Love and live this gospel!
Christ is our righteousness! Not our good works. We can never replace what Christ has done. We can never undo what Christ has done. Say it to yourself...over and over. Say with John Bunyan...My righteousness is in heaven...the same yesterday, today and forever! Listen to John Piper once more from the same sermon...
So I say it again: what God wants us to understand from Romans 8:1 when he says through the apostle Paul, "There is therefore now no condemnation for those who are in Christ Jesus," is that all of God's condemning wrath and all of his omnipotent opposition against us in our sin has been entirely replaced by almighty mercy and omnipotent assistance. In Christ Jesus God is always for you. Always! This is where Paul is going in Romans 8. He gets there in verse 31 and says, "What then shall we say to these things? If God is for us, who is against us!" His point is that in Christ Jesus "no condemnation" means that God is always omnipotently for us and not against us. Always!Hold on to that truth. Rejoice in it. Exalt it. Love it. Live it today.