Colossians 1:24 – Now I rejoice in my sufferings for your sake, and in my flesh I am filling up what is lacking in Christ’s afflictions for the sake of His body, that is, the church
Remember all the afflictions that Jesus had to experience while going through the crucifixion? There was a specific agony that He did not experience
John 19:33 – But when they came to Jesus and saw that He was already dead, they did not break His legs. 34 But one of the soldiers pierced His side with a spear, and at once there came out blood and water
So while writing Colossians 1:24, Paul is reflecting back on all the events surrounding Jesus’ death and remembers that Jesus’ body suffered the blow from the spear
Colossians 1:24 (rephrased) – Now I rejoice in my sufferings for your (the believers in Colossae) sake, and in my flesh I am experiencing and going through a lot of pain because of His name. Just as Jesus’ body received the spear that He Himself did not experience, so it is that the pain that I am going through is associated with that specific event, because all my persecution finds its rightful place filled into Jesus’ story where the body of our Lord received blows that He Himself did not feel. Therefore, my afflictions are associated with and filling up what was lacking in Christ’s afflictions
Jesus, hanging as a corpse, silently prophesied that His own body (Jew and Gentile believers) would be included into His crucifixion story and would be allocated the glorious honor of sharing in suffering with Him
1 Peter 4:13 – But rejoice that you share in the sufferings of Christ, so that you may be overjoyed at the revelation of His glory