In other words Shad you are saying that since we have been made righteous by God's grace then there is no longer need for repentence? Do you realize that what you are saying echoes the very sentiment, that because we are God's elect we are somehow exempt from the the scrutiny and judgements of God, the EXACT same sentiment which not only ushered in the Babylonian Exile but also caused the Jewish leadership to stand in oppositon to Christ?
We are not exempt from the conviction of the Holy Spirit nor of God's chastening, nor of the laws of sowing to the flesh. If we rebel in our heart against the word of God in any area, bitterness can settle in and the conscience can be seared because of pride as we stop receiving grace. This happens to a greater degree to those that have not been regenerated and they continue to reject the work of the Holy Spirit's conviction to bring them to the salvation of Christ. This is why the writer of Hebrews was so dogmatic in his approach with the Jews that were under the old system but were being brought out of it through the pre-salvation work of the Holy Spirit and bringing them to Christ.
The law could have brought them to Christ as a schoolmaster / Gal 3:24,25 but because they received their righteousness from the law they rejected Christ and the righteousness that comes by faith. So now a greater conviction than the law is convincing them of Christ and if they reject that conviction and turn back and fall away (aside) from that measure of grace, it would very difficult to renew them back to this place of repentance. Some are going to say that the word is 'impossible' and it does not mean difficult and those that reject this conviction and crucify Christ afresh cannot ever be saved through Christ.
If it means impossible and not difficult then perhaps we have to conclude that with God
NOT all things are possible, but that is not what is says / Mt 19:26, Mk 9:23, 19:27, 14:36. Are we going to say that God does not have the power through His mercy and grace to soften the hardest of hearts and have mercy on who He will have mercy / Ex 33:19, Rom 9:15-18? It is not in the power of our hands to decide on whom God will harden and on whom He will have mercy.
It took a divine intervention on the road of Damascus to get Paul's (Saul) attention with a blinding light and getting knocked off his horse and hearing words from Christ in heaven, that put him in a place of humility. Paul was not seeking God or doing that on his own nor did he have any intention to do it. God doesn't always use this approach to get the attention of a religious Jew (or Gentile) who was breathing out threatenings and slaughters against the disciples of the Lord / Acts 9. Perhaps Paul was beyond conviction and needed this kind of intervention right from God Himself. The facts of what happened are not debatable because it was God's choice to raise him up not matter what state his heart was in.
When David's son, that he had with Bathsheba, was sick and near death, David would not eat and He prayed for him for seven days, even though the prophet Nathan told him that God was going to take the boy. After the boy had died David was asked by one of the servants why he weeped for the child while he was alive but rose and ate when he was dead. This was David's reply in 2Sam 12:22;
'And he said, While the child was yet alive, I fasted and wept: for I said, Who can tell whether GOD will be gracious to me, that the child may live?'
Today we would have people explaining and analyzing David's behavior as some kind of 'post traumatic syndrome' or that he was in denial of the inevitable. They would say that his mind and actions were consistent with a grieving father over the fatal sickness of his child. They would also add that this disposition and strange behavior was complicated by the guilt and shame of having Uriah murdered, the woman's husband that he had an adulterous affair with that produced this sick child. The common person would say that he got what he deserved and should go to prison for what he did. The average Christian would have shunned him and said that he has disqualified himself from his position of leadership and who knows what else they would say these days. Maybe they would want him tried for murder or to get rid of that wh__e Bathsheba, but certainly never to be in a place to teach transgressors God's ways / Ps 51:13.
But David was in his right mind and knew that the heart of God was gracious and of tender mercies and he was going to appeal to Him and see if the Lord would be gracious to him and not take the boy. We keep going after the mercy of God, every morning, every noon and every night because His mercy endures for ever / Ps 136. If it was not for the Lord's mercies we would be consumed / Lam 3:22.
