Here are two easy ways to avoid preaching behavior modification:
More at the link.1) Exalt the Gospel, not Law – A mistake that many pastors make is that they talk too much about what is “right” and “wrong” and take moral stands on gray issues. Many congregants need a wake-up call to whatever sin they have in their life, but the thrust of your advice should not be about quitting the behavior, it should be about the grace of Christ and why His way is better. Otherwise, you enlist a church of robots who are programmed to follow all the rules self-righteously but have no idea about the beauty of grace. People must realize that freedom in Christ necessitates freedom from having to obey like a threatened slave. Furthermore, if the free grace of God is not the lens by which our people see the world, they will come up with their own definition of “good” which will only lead to them getting by day-to-day through the self-made idol of performance. As Spurgeon once said, “Love God, then do whatever you want.”
2) Magnify the Supremacy of Christ – There is a great need in our society for Christ to be enough. With every new self-help book and Oprah Winfrey wannabe, people are finding more places to run to rather than Jesus. It is a shame and an indictment on the church. We spend far too much time pounding their heads with how stupid they are for messing up rather than teaching them about the everlasting joy of following Christ. If our people are not aware that the grace of Christ is sufficient, they will eventually grow tired of trying to impress Him.