Devotion is a necessary and unnoted part of life. We all need something to drive or guide us to live and love. St. Paul wants us to think about the object of our devotion. Does it lead to life or death? Paul sees sin as not a bunch of mistakes, but as a life devoted to the things of death. That will cause us to do mean and rotten things. Devotion to Christ is a whole different thing. The difference is very good news.