The story is told of a thrifty man who one day decided to save money on donkey feed. Every day, he would add increasing amounts of sawdust into the donkeys feed. Because the process was gradual, the donkey did not notice any difference as he cleaned up his manger. The mans plan was working well, until the donkey suddenly died because of living on 100% sawdust.
Similarly, spiritual food that contains the pure Word of God, once mixed with worldly sawdust [watered-down or social gospel], will eventually lead to spiritual death (2 Peter 2). It is indeed sad to see some members of the church act as though they cannot understand why so many spiritually malnourished Christians die [abandon the Lords church] even after being members of the church for many years.
The Psalmist tells us that Gods word is lamp to the feet and a light to ones pathway (Psalm 119:105; cf. Proverbs 6:23). However, how can members of the Lords body make application of that light in their everyday living, if they remain ignorant of that light? (Hebrews 5:12-14). What is the use of chiding weak Christians about their little faith, if spiritually strong Christians do not teach them enough of the pure Word for them to be able to develop strong faith? (Psalm 51:12-13; Romans 10:17; 2 Timothy 2:1-2).
All of the church pep-rallies, sermons, and lectures about Christian duty, wont do much good for weak-in-the-faith Christians, until they are taught the pure word of God (Proverbs 30:5; Psalm 19:7-8).
Brethren, if there is any sawdust in our spiritual diet, we need to get rid of it, and start feeding our spiritually weak brethren, the pure milk of the Word (1 Peter 2:2), gradually bringing them up to the strong meat of the Word (Hebrews 5:14 KJV), so they might grow into spiritually mature workers for the Lord and His church (1 Peter 2:1-2; Ephesians 4:11-16; 2 Peter 3:18; Colossians 1:3-10).