"Now I rejoice in my sufferings for your sake, and in my flesh I complete what is lacking in Christ's afflictions for the sake of his body, that is, the church, of which I became a minister according to the divine office which was given to me for you, to make the word of God fully known, the mystery hidden for ages and generations but now made manifest to his saints." - Colossians 1:24 (RSV)
This passage is often very confusing for Protestants, and some Catholics, as they do not know what to make of Paul's words. I am addressing it here, the only such verse treated with such depth apologetically on our website, because this small passage speaks a great deal to the organic unity of which we view scripture.
The reason it is so confusing to many Protestants is due to the question it raises about the sufferings which we endure and its comparison to the cross of Christ. Both Eerdmann's and the Oxford Commentaries on scripture note, and rightly so, that there is nothing left to be accomplished by Christ for our covenantal salvation, and that this verse must make reference to the whole body of Christ. This is also the common interpretation of most of the Protestant scholars. However, beyond this there is not much on the subject that contributes greatly to an understanding of the passage.
The Catholic commentaries, such as the
"Can it be that Christ's passion alone was insufficient to save us? It left nothing more to be done, it was entirely sufficient to save all men. However, for the merits of the Passion to be applied to us, according to St. Thomas (Sum The. 3, 49, 3), we need to cooperate (subjective redemption) by patiently bearing the trials God sends us, so as to become like our head, Christ" (St. Alphonsus, Thoughts on the Passion, 10).
There is an understanding here that our sufferings for the sake of Christ are not without any merit, however they cannot merit what Christ does so on the cross. They are a part of our faith that we have in God, bearing witness to the whole truth of the Gospel, even in the afflictions of our bodies. In the cross, suffering is redeemed and God can use suffering to work good and greater glory for His name.
Think of it on this level also. When we pray we do so because we believe our prayer is going to be effective. When we pray for another, and God responds to that prayer, God has given grace to another through our efforts. If we perhaps did not pray, God may have chosen not to act. We may then also, when we suffer, offer that suffering to God, upon which it can be used for the good of the body of Christ. As a believer, like prayer, our afflictions can be used by God for others, not on our own, but in our faith and in cooperation with God. Our actions can never be separated from the grace and actions of God as if we could merit anything for the body of Christ apart from the grace and will of God. All of this then rests on the idea of cooperation with God's will.
Think of it finally with this illustration. In the movie "Spiderman" the principal character had a choice at one point when a boxing manager was robbed. He could cooperate with the efforts of the police and the business and stop the man, or he could let the man go and get away. If he cooperated with the others, he would stop the robber, if he did not, the robber would get away. If the police however had no intention of stopping the robber, than his efforts would be futile. Likewise, if we choose to cooperate with God and offer up our own afflications for the body of Christ, God may chose to use them for such a purpose, because our sufferings, in Christ, are redeemed. If we chose not to cooperate with God, God will not force us to do so.