Colossians 1:23b-29 At the end of vs. 23 and his wonderful treatise on perseverance, Paul moves away from the topic of reconciliation and begins describing his role as a servant of the Gospel. This seems to be an abrupt shift in focus- but Paul desperately wants these Colossian Christians to know why he is so grateful and willing to serve God in the gospel, in spite of great adversity.
One of the most obvious truths of Bible Christianity is simply this: those whose lives have been transformed by grace, will deeply desire to share this grace with others! Paul keeps coming back to this theme- we are merely links in the great chain of grace. Therefore, Paul transitions in his thoughts at the end of vs. 23 by describing himself as a servant of the gospel, blessed to be able to spread this wonderful message far and wide throughout the Roman empire.