The focus of our life as disciples of Jesus, is to be 'on Jesus' - he is to be our focus! It's all about Jesus. When we get distracted by things that draw us away from the things of God, we need these words of Paul to refocus our life. Let Jesus rule in our hearts.
In verse 16 he rephrases ; "Let the message of Christ dwell among you richly as you ..." We know what it is to let Jesus rule in our heart, through the New Testament scriptures; through the words and actions of Jesus. Its why Jesus told the apostles to teach people to obey everything I have commanded. This obedience to the things of Jesus is something made possible only through the work of the Holy Spirit in us, empowering us and gifting us.
Further on in this passage, the Apostle Paul makes reference to the typical secular household codes pertaining to wives and husbands, children and parents, slaves and masters. This devotion today is not the place for a detailed discussion on what these relationships ought look like, and why he writes the way he does, but it is the place to reflect on the clear, big picture teaching that Paul offers. Paul does not follow the secular example of teaching only on the dominant person in the partnership; if he had he would simply commend the dominance of husband, parent and master. On the contrary, Paul writes nothing controversial about the wives or children or slaves; he simply states what is the status quo for that day. As for what the husbands, parents and masters are to do, he radically reframes the expectations. In the corresponding passage to this one in his letter to the Ephesian church, Paul starts the discussion by reminding them all that they are to live lives of mutual submission and this too is the expectation in Colossians.
The discussion about how those involved in the above mentioned 'household codes' are to relate to and treat each other, stems from what he writes about letting Christ rule in their hearts. As you live as a disciple of King Jesus, what reframing of your relationships and attitude to others needs to take place so that you genuinely live in such a way as to allow Christ to rule in your heart; what is the Spirit of Jesus saying to you today?