In the days of his flesh, Jesus offered up prayers and supplications, with loud cries and tears, to him who was able to save him from death, and he was heard because of his reverence. Although he was a son, he learned obedience through what he suffered. And being made perfect, he became the source of eternal salvation to all who obey him, being designated by God a high priest after the order of Melchizedek. About this we have much to say, and it is hard to explain, since you have become dull of hearing. For though by this time you ought to be teachers, you need someone to teach you again the basic principles of the oracles of God. You need milk, not solid food, for everyone who lives on milk is unskilled in the word of righteousness, since he is a child. But solid food is for the mature, for those who have their powers of discernment trained by constant practice to distinguish good from evil. (Hebrews 5:7-14)
The first few verses above are some of the most difficult verses in the Bible. Jesus is God and yet Jesus "learned obedience" through His suffering? He was "being made perfect"? I thought Jesus was always perfect? Theologians far more learned and wise than I am have wrestled with these questions for two millennia so I am not going to try to make a definitive statement here. Certainly Jesus is eternally God but also Jesus became flesh and dwelt among us, becoming like us. The fancy term for this is the "hypostatic union", the union of 100% God and 100% man. We also know that Jesus "emptied himself"
Have this mind among yourselves, which is yours in Christ Jesus, who, though he was in the form of God, did not count equality with God a thing to be grasped, but emptied himself, by taking the form of a servant, being born in the likeness of men. (Philippians 2:5-7)
Somehow, someway that neither I nor anyone else in this life will understand, Jesus became both God and man at the same time, God in human form, perfect being and Creator that needed to eat and sleep. God as Son who cried out to, submitted to and prayed to God as His Father and yet is co-equal with that very same God in power and holiness and eternality. The key words to getting an understanding of this are at the beginning, "In the days of his flesh", words to speak to the uniqueness of Jesus entering time and space to take on flesh. That is a terribly poor take on this topic but this series is not intended to wrestle with the biggest questions.
As for the rest of the verses? Well that is pretty straightforward and easy to understand. When I read verses 12-14 it is like the author of Hebrews was looking into the future and seeing the church of today. The church, at least as we understand it, is full of people dull of hearing and being spoon fed milk week after week. People who have been "in church" for decades and barely grasp the elemental principles and teachings, much less are prepared to teach. The Western church, lazy and flaccid in our opulence and comfortable with our prominent and protected position in the culture, has trapped countless Christians in a lifetime of perpetual spiritual infancy and worse yet given false hope to so many who have been given a fatally flawed view of the Gospel and the way of the cross.
One of the great scandals of the church is how few Christians even approach a place of maturity where they become teachers. We have an overabundance of over-educated clergy that should be equipping the church (Eph 4: 11-16) but instead are largely bogged down in preparing sermons and carrying the entire burden of ministry for those who hired him.
Wake up church! Get back to the basics and then get rid of the traditions and anything else that keeps people in infancy. Give people the tools they need to do the work of ministry and let them go! A child that never gets out of the high chair will never learn to walk and if he is never given anything but milk he will never learn to chew meat. People, put down the spoons and pick up a fork and a knife and dig in!