The role of a priest is to represent the rest of the community and make offerings and sacrifices on their behalf to God. That's why the Methodist Church doesn't have priests, because it doesn't believe that we need a special priesthood to present our offerings and sacrifices. Instead, it believes in 'the priesthood of all believers'.
People sometimes say 'the priesthood of all believers' means that everyone can make their own direct approach to God. In fact, it does not mean that. It means that the whole congregation, gathered together in worship, can approach God without having to depend on a priest to represent them.
Instead of priests, the Methodist Church calls people to be ministers. The difference is that, instead of presenting sacrifices and offerings to God on behalf of the people, a minister is a servant of God and a shepherd or pastor to the congregation.
Other churches do have priests, of course. The Orthodox, Roman Catholic and Anglican Churches call people into the priesthood and give them special authority to present the offerings and sacrifices of the people to God. In Anglican Churches, the priest first presents to God the people's gifts, or offerings, of money, bread and wine, and then presents the people themselves as a holy and living sacrifice to God.
That isn't so very different from what happens in a Methodist Church, except that in a Methodist service the whole congregation offers its gifts and itself as a holy and living sacrifice. The minister presides at the service, but only for the sake of good order and not because he or she has any special kind of priestly function or status.
Is this supposed difference between Anglican priests and Methodist ministers a real one or an imaginary one? You might think that telling the difference between what ministers and priests are actually doing in the service of Holy Communion is a bit like working out how many angels can dance on the head of a pin!
Whatever Methodists may believe about priests, the writer of the Letter to the Hebrew or Jewish Christians does believe in priesthood and he knows that his readers believe in it, too.  In Christian Churches, anyone can be called by God to be a minister or priest, but in orthodox Judaism only a descendant of Aaron, the brother of the Prophet Moses, could become a priest. No one else could make offerings and sacrifices to God on behalf of the people.
This didn't mean that someone had to be especially good in order to become a priest, nor do you have to be especially good to become a Christian priest or minister today. On the contrary, an ordinary person, subject to the same weaknesses and failings as everyone else, is better qualified because they are able to understand how we feel. They can sympathise with us when things go wrong and we feel we need God's forgiveness. And they can appreciate how hard it is, sometimes, to understand the mind of God and the meaning of life.
There was a lot of publicity recently about the vicar who has had to stop functioning as a priest, for the time being, because she can no longer say the words of forgiveness which Christian ministers have to speak on the congregation's behalf during the service. Her daughter was killed by one of the suicide bombers last July, and she does not feel able to forgive him, at least for the moment. But that's all right. We can't expect ministers and priests to be any different from the rest of us. When we would feel angry and resentful, they will probably feel the same. If we sometimes find it hard to forgive, so will they.
Most Jewish people at the time of Jesus were happy to accept that, although anyone called by God to the priesthood need be no better than the rest of us, they did have to be members of the clan of Aaron. But not everyone felt that way.
The Book of Genesis tells the story of a mysterious priest called Melchizedek.  He lived long before the time of Moses and Aaron. He wasn't even a descendant of Abraham, the father of the nation of Israel. But the legend tells us that he was a priest of the Most High God, the maker of heaven and earth. Like a priest at a communion service he offered bread and wine to God on behalf of the people, and he gave Abraham God's blessing.
As it happens, Melchizedek had two jobs. He was a priest, but he was also the King of Jerusalem, so whenever the kings of Israel and Judah wanted to make their own offerings and sacrifices to God – without a priest to stand in for them – they appealed to the example of Melchizedek. What was good enough for him was surely right for them.
It wasn't just kings who appealed to the example of Melchizedek for support. Anyone who wasn't a descendant of Aaron, but who felt that God was calling them to be a priest, could claim to be a priest like Melchizedek. At the time of Jesus a group of people called the Essenes became dissatisfied with the Temple in Jerusalem and its priesthood. Deciding that the Jerusalem Temple was hopelessly corrupt, the Essenes established their own community – deep in the Judean desert near the Dead Sea – at a place called Qumran. There they set up their own order of priests, who offered gifts and sacrifices to God for them following the example of Melchizedek.
And, of course, if the first Jewish Christians wanted to describe Jesus as a priest, he could only be a priest like Melchizedek because he was a descendant of David, not a descendant of Aaron. And like Melchizedek, he was a king as well as a priest, for the first Christians believed that Jesus was the Messiah, the anointed leader or king of God's chosen people. Again, like Melchizedek, Jesus had offered gifts of bread and wine to God when he broke and blessed the bread, and blessed the cup of wine, at the Last Supper in Jerusalem.
Like any good priest, Jesus offered prayers and supplications to God. But, unlike even the best of the priests in ordinary temples and churches, the first Christians believed that Jesus had been reverent and obedient to God to the point where he was able to be made perfect in suffering, for his final act of obedience had been to offer the ultimate sacrifice to God.
Believing that he had been sent with a mission to reveal God's unconditional love and compassion for human beings, Jesus had become convinced that the only way he could reveal the depth of God's love was to offer his own life as a sacrifice. So he allowed himself to be arrested and put to death by his enemies in the hope that the human race would see in this self-sacrifice a sign of God's forgiveness and an opportunity to make a new beginning in their relationship with God.
Other priests have offered animals, money or gifts of grain and sweet smelling incense as symbols of the people's devotion to God. Jesus offered himself, as a sign of reconciliation between God and humankind. For the Jewish Christians, to whom the Letter to the Hebrews is written, this made Jesus not just a priest like Melchizedek, but the perfect priest who offers the perfect sacrifice. After this, the only sacrifice that is necessary for Christians to make is the sacrifice of our grateful hearts and minds. All that we have to do is to obey Jesus, and live for him, in order to be put right with God for ever.
In the Eucharist or service of Holy Communion, we remind ourselves of Jesus' offering of himself and lay claim to the power of that sacrifice to change our lives and our relationship with God. Orthodox and Roman Catholic Christians believe that, in the Prayer of Thanksgiving, the priest is offering the sacrifice of Jesus to God again. For Methodists and Anglicans, the prayer is more usually understood as a reminder – a calling into the present – of what Jesus did for us once and for all time on the Cross. But all Christians are called to respond to the prayer by offering themselves as a holy and living sacrifice to God, for Jesus' sake. If we will do this, if we will put our trust in Jesus, he becomes for us the source of new life, and a new and everlasting relationship with God becomes ours for ever.
 Hebrews 5.1-10
 Genesis 14.18-20