We have much to say about this, but it is hard to make it clear to you because you no longer try to understand. 12 In fact, though by this time you ought to be teachers, you need someone to teach you the elementary truths of God’s word all over again. You need milk, not solid food! 13 Anyone who lives on milk, being still an infant, is not acquainted with the teaching about righteousness. 14 But solid food is for the mature, who by constant use have trained themselves to distinguish good from evil.
‘PILGRIMS SHOULD MAKE PROGRESS’: Warren W. Wiersbe.
One reason people fall away from the faith is because they stop trying. An old hymn says, ‘It is not trying, but trusting.’ In truth, it is both. Someone wrote that grace is not opposed to effort; it is opposed to works (i.e. as a way to salvation). It takes prayerful, trusting, diligent work in order to grow as a Christian. Someone who insists on just sucking on a baby milk bottle teat, because it’s easier than chewing solids, is going to fail to mature into the person God intends them to be.
One mark of maturity is that you become a ‘teacher’: not necessarily from the pulpit. But you are able to take a younger Christian under your wing and mentor them – even in an informal way.
Another mark is that you don’t just read the Bible; you constantly, practically, put it to ”use”.
‘As we grow in the Word, we learn to use it in daily life. As we apply the Word, we exercise our ”spiritual senses” and develop spiritual discernment. It is a characteristic of little children that they lack discernment. A baby will put anything into its mouth. An immature believer will listen to any preacher on the radio or television and not be able to identify whether or not he is true to the Scriptures…As we feed on the Word of God and apply it in daily life, our inner ”spiritual senses” get their exercise and become strong and keen.’ (Warren W. Wiersbe: ‘New Testament Commentary’, pp.816/817).