Growing spiritually as God’s child is imperative. It is not a divine suggestion or recommendation. It is an urgent, indispensable necessity. The writer of Hebrews emphasizes three potent reasons why this is true.
First, a lack of spiritual growth creates sluggishness and degeneration in your heart (Hebrews 5:10-13). Such dullness of hearing makes more advanced doctrinal instruction unprofitable. The penman of Hebrews wanted to begin an in-depth consideration of Jesus’ High Priesthood (5:10), but such would be like trying to force feed steak to a nursing baby (5:12). Continuous spiritual sluggishness and degeneration grow thorns and briers, whose end is to be burned (Hebrews 6:8).
Second, a lack of spiritual growth increases your vulnerability to falsehood (Hebrews 5:13-14). Being able to discern both good and evil is the result of diligent spiritual growth, not lucky guesses. The spiritually immature are far more likely to be “tossed to and fro and carried about with every wind of doctrine, by the trickery of men, in the cunning craftiness of deceitful plotting” (Ephesians 4:14). Not being able to weather such spiritual realities invariably results in shipwreck (1 Timothy 1:19).
Third, spiritual growth is a “use it or lose it” reality (Hebrews 6:1-8). There are only two possible directions you can be traveling in life—toward heaven on the narrow way or away from heaven on the broad way (Matthew 7:13-14). Like your outer man, your inner man needs food and exercise in righteousness. Therefore, you either use today to grow spiritually, or you lose it. Yesterday has no “mulligans”.
It makes no sense to become a child of God with all its glorious blessings and then fall away (Hebrews 6:4-6). This is the worst possible spiritual state you can be in (2 Peter 2:20). The only way to prevent such a horrific condition is to grow in the grace and knowledge of our Lord and Savior Jesus Christ (2 Peter 3:18).