Heb 5:12-14 For though by this time you ought to be teachers, you need someone to teach you again the first principles of the oracles of God; and you have come to need milk and not solid food. 13 For everyone who partakes only of milk is unskilled in the word of righteousness, for he is a babe. 14 But solid food belongs to those who are of full age, that is, those who by reason of use have their senses exercised to discern both good and evil.

The Hebrew writer helps us to see some characteristics, signs or symptoms of spiritual immaturity as he reproves these brethren to whom he writes. We see that two of the characteristics are the need for someone to teach them again the first principles (because they had become dull of hearing), and the fact that these Christians should have been teaching others, but weren’t. Both of these characteristics are applicable in the Lord’s church today, as manifested by the desire by many to go into denominationalism, as well as the failure of members of the church to teach others the gospel of Christ.

Another characteristic of spiritual immaturity is the desire for milk, and not for meat. If we were rearing children, and the child only wanted milk after the first couple of years, we would know that something was desperately wrong. Children grow up physically by eating pabulum, and then the solid food adults eat. In the church, babes in Christ need to desire the sincere milk of the word for some time (1 Peter 2:2), but there comes a time when Christians need to grow up and eat the meat of the word. Milk is necessary for a while, but one must eat meat if they would grow.

Christians should desire the milk, but they must grow to eat other things, so that their faith and confidence in God will continue to grow. It is my opinion that the reason why some never grow in the church is because they are satisfied with what they have, and want nothing else. They don’t want to grow up. They don’t want to act mature, even though they really can’t make it in the world if they don’t. They want to be pampered, petted and promoted, rather than allowing God to have the place he deserves. While babes, it is all about them – when mature, it is all about HIM (GOD). Childishness and selfishness are characteristics of the immature, and if we don’t tolerate it among adults in the world, we should not tolerate it in the church if one has had the time to grow in the faith. Yet we do, often to the detriment of the church.

Solid food belongs to those who are mature, and to those who are exercising their faith. We can talk about being dull of hearing, not growing to teach others and desiring the milk of the word, and these are real symptoms of spiritual immaturity. But another major symptom is failing to use (exercise) what we know.
We know that if we don’t exercise a muscle for a period of time it shrinks and grows atrophied. It has to be exercised if the muscle will endure and grow to what it is able to do. The same thing with the body of Christ. We have to exercise what we know.

For some reason, however, it is easier to revert back to what we did in the world. One of the greatest examples of this is found in Matthew 18:15-17, where Jesus tells us how to handle a problem we have with a brother. If we are sinned against, it is OUR DUTY to EXERCISE what Jesus has said and go and talk with the brother in question. But often, even though we know that is what God has said we must do, when we get hurt we talk to everyone but that brother. We get the congregation astir, and things get said that should never be said. The church is hurt because of immaturity – we are hurt because of immaturity, and God’s way suffers. We excuse our failure to obey because we fear confrontation; yet misunderstandings erupt that causes more confrontation and pain.

Spiritually mature people apply what they have learned to their lives and it is evident by their manner of lives. Their lives are shown by their fruits that they bear. Let us work for spiritual maturity by listening to God’s Word, by growing to teach others, by desiring more than the milk of the word, and by exercising what we have learned for the glory of God! He deserves the best we can offer.