I apologize in advance if this has been responded too.
This is a misunderstanding on your part. We do not add to the finished work of Christ…but we produce the life of Christ in us…to suffer for our brethen…to love…No. It means that Christ’s suffering and death must be reproduced and filled up in the Church and if some are slacking off, that means others must become more like victim-souls, willing to bear a greater burden, willing to shoulder with love, as Galatians 5 speaks about the love, “Love bears one another’s burdens.” We do that just as 1st John 5 speaks about how we can pray for others and get them back on track after their venial sins have been committed. So likewise we can suffer on behalf of others. That’s what fathers and mothers do all the time. And God calls us to do that in the supernatural family, as well, on behalf of our brothers and sisters and our spiritual children, as well. That’s what Paul takes for granted when he makes such an outlandish statement. Outlandish only for those who do not recognize the essential need for suffering. (
catholiceducation.org/articles/apologetics/ap0091.html)
You should read 2Samuel 12 first…
5 David burned with anger against the man and said to Nathan, “As surely as the LORD lives, the man who did this must die! 6 He must pay for that lamb four times over, because he did such a thing and had no pity.” …**13 Then David said to Nathan, “I have sinned against the LORD.”
Nathan replied, “The LORD has taken away your sin. You are not going to die. **14 But because by doing this you have shown utter contempt for[a] the LORD, the son born to you will die.”
15 After Nathan had gone home, the LORD struck the child that Uriah’s wife had borne to David, and he became ill.
This event precedes Psalm 51.