Just as an infant is fed with milk to grow by, we spiritually are to desire the sincere milk of the word to grow more in the wisdom of the Lord(1 Peter 2:1-3).While some stay at a level of infancy in Christ, others study and meditate upon the word and grow. If we choose sin and a life away from God and live what God considers carnally (fleshly) then we remain unable to accept what scripture calls the meat of the word that is the solid food that can cause us to be strengthened (1 Corinthians 3:1-3). And I, brethren, could not speak unto you as unto spiritual, but as unto carnal, even as unto babes in Christ. I have fed you with milk, and not with meat: for hitherto ye were not able to bear it, neither yet now are ye able. For ye are yet carnal: for whereas there is among you envying, and strife, and divisions, are ye not carnal, and walk as men?
Scripture teaches us if we learn of Him but then not continue learning we are considered unskillful in the word and become as babes again in need of milk and are not trained to discern between good and evil as when we have strong meat that gives us the strength that enables us to teach others(Hebrews 5:12-14). For when for the time ye ought to be teachers, ye have need that one teach you again which be the first principles of the oracles of God; and are become such as have need of milk, and not of strong meat. For every one that useth milk is unskilful in the word of righteousness: for he is a babe. But strong meat belongeth to them that are of full age, even those who by reason of use have their senses exercised to discern both good and evil.