A journalist once asked Carl Sandburg, "What is the ugliest word in the English language?" After a few minutes Sandburg replied, "Exclusive." The ugliness of exclusive depends upon whether we are among the included or the excluded. We pride ourselves on being members of exclusive clubs, living in exclusive neighborhoods, dining at exclusive restaurants, vacationing at exclusive resorts, belonging to exclusive churches. Being an insider carries with it a sense of pride and security. Most of us, however, have been excluded often enough to agree that exclusive is an ugly word. When we are among the marginalized, the rejected, the pushed-aside or the left-out, it hurts!
The conflict in the early church centered on the question of who is in and who is out. Are gentiles to be included? Peter and Paul debated that one until Peter had a dream and concluded that "God shows no partiality" (Acts 10:34). The Book of Acts is the story of God's grace through the Holy Spirit, pushing the early church out to the margins and breaking down the barriers among the people.
Judging people by whether or not they are "one of us" thwarts God's reign of justice, generosity and joy. The disciples missed the power and victory of God's liberating presence in the man casting out demons. Their assumption that only those "following us" could cast out demons blinded them to God's presence in another. Rather than being grateful that demons were cast out, they were upset that the healing was done through someone outside their group.