The disciples sent by Jesus have as their task to prepare his arrival. It will not be an easy task, and do not need great resources to carry it out. The disciples of Jesus can not take anything, no bag, no sandals. They can only and must bring peace. This means that they must trust in the hospitality of the people. For the disciple who goes with nothing, hardly carrying peace, shows that he trusts people. He trusts that he is going to be received, and people feel respected and confirmed. Not greeting anyone along the way probably means that they should not waste time with things that do not belong to the mission.
The Kingdom of God that they must announce is not a doctrine, nor a canon law, nor a catechism, but a new way of living and coexisting from the Good News that Jesus brings us: God is Father and therefore we are all Brothers and Sisters. Educating for the Kingdom is not in the first place teaching truths and doctrines, but it is a new way of living, a new way of acting and thinking.