One of these is a nice "connection of the dots" concerning the Catholic practice and piety around "redemptive suffering." By this, I mean the pious belief that we can unite our suffering to Christ's and that, when so united, this suffering can have some redemptive effects. The idea is that we "offer it up," that is, offer up the suffering in our daily lives as a sacrifice to God, for the salvation of souls.
Here is the relevant passage from the book:
"In Colossians 1:24-26, Saint Paul writes, 'Now I rejoice in my suffering for your sake, and in my flesh I am filling up what is lacking in the afflictions of Christ on behalf of his body, the church, of which I am a minister in accordance with God's stewardship given to me to complete for you the word of God, the mystery hidden from ages and from generations past.' This almost sounds like heresy. Is Saint Paul saying that Christ's passion and death are missing something? Absolutely not. Christ redeemed the sins of generations past, present, and future. Saint Paul is telling us that we're the body of Christ. When we unite our suffering to Christ's suffering, we too can help save souls. This union is key. Here is how the Catechism of the Catholic Church explains it: 'Suffering, a consequence of original sin, acquires a new meaning; it becomes a participation in the saving work of Jesus.' (Catechism of the Catholic Church 1521)"The concept of redemptive suffering is therefore rooted in the in the idea that we are Christ's body, and that therefore what we suffer as members of His body, He suffers (see also Matthew 25:31-46 and 1 Corinthians 12:12-27). Christ's suffering is completed, final, once-and-for-all, yet is is also being completed in our lives. Another way of looking at this is that suffering is a necessary consequence of Original Sin, not merely as punishment, but rather as redemption. Our suffering is not just an arbitrary punishment meted out by God, but instead it is Christ's suffering echoed in our lives* because we are members of His body. He suffered because we suffer, but on the other hand we are suffering because He has suffered.
*Or Christ's suffering anticipated by those who came before His Incarnation.