The author implores his readers to quit being sluggish in their spiritual growth and dull of hearing God's Word. He exhorts them to move on to spiritual maturity. God will do His part if we do our part in growing spiritually.
This lesson deals with a very difficult passage of scripture that says it is impossible to be renewed unto repentance. What is it that we cannot repent of? We can repent of sin, but we cannot repent of the lost time, lost fellowship, lost opportunities, etc. as a result of spiritual regression.