Like newborn babies, crave pure spiritual milk, so that by it you may grow up in your salvation, now that you tasted that the Lord is good.
- 1 Peter 2:2
We need spiritual milk to grow, which is God's Word.
Scripture teaches us, "Anyone who lives on milk is an infant.”
We are to move from milk to meat.
The metaphor is simple: spiritual maturity is a process. Just like a child, we shift from milk to meat.
This is like growing from spiritual adolescence to spiritual adulthood.
But solid food is for the mature, who by constant use have trained themselves to distinguish good from evil (Hebrews 5:13-14).
The spiritually mature are distinguished by the training they have received. A part of that training includes the knowledge of good and evil and to differentiate between the two. This knowledge is not the knowledge of man, but the knowledge of God.
Why do you spend your money for that which is not bread and your labor for that which does not satisfy? Listen diligently to me, eat what is good, and delight yourselves in rich food. (Isaiah 55:2, ESV)
The immature waste their money and time on things that do not bring Godly satisfaction. Is this you?
The anecdote is to listen to God diligently and eat what is good. And when you delight in the richness of the Word of God, you will grow into a fully mature son and daughter of the Lord.