“Anyone who lives on milk, being still an infant, is not acquainted with the teaching about righteousness. But solid food is for the mature, who by constant use have trained themselves to distinguish good from evil” ( Hebrews 5:13-14 )
When a baby is born they are fed their mother's milk for the first six months of their lives. Then as they grow they are slowly introduced to solid food. First in the form of baby foods, pureed fruits and vegetables that are easy to swallow and digest. Then small amounts of prepared food, cut into little bits. Eventually they are given solid food, once their teeth have come in and they have learned to chew and swallow it. It is a natural process that one does not have to teach with much effort.
As children grow, they also begin to feed themselves. Every mother knows that at a certain point, the baby will not allow others to spoon feed it any longer. The child wants to use the utensil to bring the food into their own mouth. What begins as a messy process is also a necessary one. They learn coordination from working the spoon when they eat. They develop skills, early on, to feed themselves for the rest of their lives. This is the way it should be. After all, no one would want to spoon feed a forty year old baby, it would be quite embarrassing.
The same natural principle can be used for Christians. At first, they should be gathered and taught the first principles of God's Word. They should be encouraged and led into these amazing truths by those who are older in Christ. As this happens, their own skills should start to develop for reading and understanding the Word for themselves. They should ask questions seeking comprehension of what they are studying. All the while being trained through the power of the Holy Spirit to understand what has been written to them in the Scriptures. As they do this, the Lord speaks His powerful truths into their hearts illuminating their lives with this knowledge and truth.
This is a process which requires solid doctrine as its foundation. The footing must be set on the basic principles of God's Word to understand the other truths that are recorded for us. No one would give a child a steak; so in the same way a new believer must start out on the milk of the word and grow in the knowledge and truth of God.
Problems arise because we have a multitude of Christians who are not progressing in the natural process of growing up. The writer of Hebrews is chiding the people for their laziness in understanding the principle he is writing about. He told them that they ought to be teaching others by this time and yet they are still feeding on the milk of the word, needing someone to each them the very first principles over and over again ( Hebrews 5:12 ). He goes on to say that anyone in this condition is not acquainted with the teaching about righteousness. The Amplified Bible puts it this way, “For everyone who continues to feed on milk is obviously inexperienced and unskilled in the doctrine of righteousness (of conformity to the divine will in purpose, thought, and action), for he is a mere infant [not able to talk yet]!” ( Hebrews 5:13 Amp ). These are harsh words, but the truth in them rings clear, just as it is not acceptable for an adult to continue to nurse, a believer should not remain an infant in the knowledge of the Word.
The remedy to this problem is growing up! It takes time and it takes discipline to get in the Word regularly. But Jesus is the one who said, "The words I have spoken to you are spirit and they are life" ( John 6:63 ). The written word is our handbook for this life, Peter said that everything pertaining to life and godliness is found there ( II Peter 1:3-4 ). The writer of Hebrews closes chapter 5 with these words, “But solid food is for full-grown men, for those whose senses and mental faculties are trained by practice to discriminate and distinguish between what is morally good and noble and what is evil and contrary either to divine or human law” ( Hebrews 5:14 Amp ). As we grow, the more skilled we are in the word, the more we will understand these truths when we hear or read them. We will not need anyone to first explain the foundation again, instead we will build upon it entering into the fullness of God with the complete understanding that belongs to the spiritually mature.