This is why people sometimes look back to when they were first "saved" as something better than what is happening now. In the beginning they received the gift of the Holy Ghost with little or no knowledge. As they gained knowledge through study and through the sermons of men [eating the flesh of Jesus] but did not also stir up and increase in the Holy Spirit [drinking the blood of Jesus] they apparently stood still... but actually moved backwards toward what they were before they met the Master. Staying on milk alone may be good for a baby, but babies need to grow. Jesus put it like this:
"Then Jesus said unto them, Verily, verily, I say unto you, Except ye eat the flesh of the Son of man, and drink his blood, ye have no life in you.
Whoso eateth my flesh, and drinketh my blood, hath eternal life; and I will raise him up at the last day." John 6:53-54
When people regularly quench the Holy Spirit, they starve the "new man" no matter how well they know the written scriptures. Quenching the Spirit is regularly practiced and taught in church settings although is seldom called that. They defined it with their preset program instead of allowing the Holy Spirit to lead them according to the program that God would supply if He were allowed to do so:
"Yea, they turned back and tempted God, and limited the Holy One of Israel." Psalm 78:41
"Quench not the Spirit." I Thess 5:19