Matthew gives instructions about how to live together. You cannot live with anyone without conflict, without someone wronging the other, because we are human beings.
These last three weeks I have lived with three groups of people.
Firstly I stayed with my family in Scotland in a remote place on the island of Mull, an owl sanctuary.
If you have a family, you have conflict. Fortunately we had two 
cottages, so when there was conflict you could escape to the other cottage. There were 4 teenagers. So there was plenty of conflict. One of the boys came into our cottage to offload, let off steam and he is very emotional. Then he went back. The conflict however smouldered and blew up back home. Eventually he apologised tho the issue is ongoing.
Crossing Mull to Iona I swerved to avoid an oncoming car trailing a boat. As I did so I went into a ditch on the left hand side so the car was lurching diagonally into a ditch. The 4 men in our party, rocked and pushed while I steered and my daughter provided necessary ballast to bring the car upright and we miraculously returned onto the road. All conflicts forgotten as we worked together in a high functioning team.
Secondly I stayed with 15 asylum seekers in the Yorkshire Dales. I was just a driver. We stayed in the oldest Quaker meeting house in the country, a converted barn, and I slept outside in a tent in the cemetery. My colleague slept outside on the grass.
There was conflict. Plenty of it. These people are deprived of money, movement, family, work, and status as they negotiate the UK asylum system. Most of the conflict centred around a woman who could not discipline her son, who kept going into the kitchen area, punched another child, wouldn't go to sleep, shouted at the adults and was generally a pain in the butt. People trying ed to negotiate the problem but it got wearing. It exploded over a small incident. The problem could not be solved because the mother refused to accept that her sons behaviour was unacceptable and she marginalised herself.
Lastly I went to Perpignan for an international conference on social documentary photo journalism. There was conflict. I was in a queue waiting for an interview with a magazine. But people who knew the organisers kept pushing in front of the queue using the old boy network to jump the queue. This was unresolved. When I was interviewed people were still barging in hoping for 5 minutes with Reuters, Getty or whatever.
Matthew records Jesus' teaching on living in community. He does not teach us to ignore inter personal conflict. He teaches us that recognising the conflict, speaking about it and forgiveness are central to the resolution of disputes. He has earlier spoken if the importance of humility, and the treatment of children. We also must not be stumbling blocks for others especially children. The consequences are dire.
There is no justice without first an open voiced telling of the wronged persons story, if the person refuses to recognise their wrong doing it becomes a community matter, possibly legal and finally the person is excluded if they refuse to recognise their wrong doing, which can mean social exclusion but also imprisonment. But Matthew is writing of church discipline.
In ourworld stumbling blocks are inevitable, but this does not mean that a person has to promote or create them; woe to the person who does.
Back to our person who has been the object of stumbling blocks! Bring the problem to light, do it privately rather than publicly. Have it out with them. If they listen to you have won them over. If s/he doesn’t listen, take a few others, (as witnesses Deuteronomy 19:15 establishing the point that a person cannot be convicted on the evidence of just one person), to confront the problem, emphasizes the need to exhaust every possibility in the effort to win back the person. Then treat him as you would a pagan or a tax collector as an outsider. This however does not mean treat him with contempt or cruelty.
In seeking to restore the brother or sister who has strayed from the faith, the Christian community seeks them out to restore them. Here the authority is given to the Christian community. The church is being given the authority to arbitrate on matters of God's will and declare a verdict on the matter (like Sharia Law). Members either confirm God's condemnation or forgiveness. Whatever you loose, abolish upon the earth, will have been loosed.
The second saying is on the authority of the church. Again, the saying can be understood in a number of ways. So, for example, the saying may give the idea that when two or more Christians believe in something in prayer, it will happen. But what about unanswered prayers? The saying may be teaching that when two or three meet in Jesus' name, God will be present, revealing God's will to them. The congregation can then pray, believing that it will be done for them.
Expanding the principle out, we have to say at these times that public statements supporting the denigration of those of colour or religion is a scandal, a stumbling block to our community, our well being. We need to call it out, before it infects us and woe to those who perpetrate Nazi and fascists ideology. It has no place in the community of Gods people and woe to such people whether they be people in our own families, people we encounter or politicians. They need to be challenged, and exercised. Woe to them! And woe to us if we tolerate stumbling blocks to our relationships and our community.
