The author of Hebrews addressed the problem of Jews who had been delivered from their sin but were falling back into their old ways. Any believer can be inclined to just go with the flow, becoming dull of hearing God's Word and then careless spiritually. When we allow our hearts to be hardened and insensitive, it makes us sluggish and even embarrassed to mature in our walk. So it is vital to be diligent to live according to what the Lord tells us. Video of this service is available:
https://www.youtube.com/watch?v=mtlQ9pWmyuI