Churches often have them. I am sure they don't mean to develop but they do and sometimes they are destructive. In saying this, sometimes the entire Church is a clique and outside people find it very difficult to fit in. This is especially the danger of smaller churches where everyone either knows or is related to everyone else. Churches don't mean to be exclusive, but they can be. The Word of God clearly states:
Be wise in the way you act toward outsiders; make the most of every opportunity. (Colossians 3:5)
The Spirit showed Apostle Paul how exclusive the Church could be, even at the beginning. Jesus did not practice exclusivity. He went out of his way to make sure that his disciples came from a varying background, and even then he only spent time alone with them to teach them the foundations. Other than that Jesus was always amongst the crowds of people who came from every background. Even though he had come specifically to deal with Israel, he still included the gentiles when they came to him. Jesus told us whoever believes will be saved.
The Church is not like the nation of Israel. That nation was given a territory and was told to be different from neighbouring nations. Israel was intended to be used by God to display his glory, to reveal himself to the world. Right from the beginning the Church was founded differently. We were not given a territory. In fact the first command given to the Church was to "go". And Jesus was serious about that. When the Church disobeyed the command and decided to stay in Jerusalem, Jesus allowed a persecution to scattered them throughout the earth.
The Church is not about physical territory but spiritual. The Church is about the heart condition of people. The Church is still the instrument to reveal God's glory to the world but it is done in the workplace, in the home, in schools, hospitals, nursing homes, marketplace, wherever Christians go so goes God's glory and power. This is why we cannot afford to become a clique like Israel was. We can't afford to have any thoughts of being exclusive. We are only special in that we accepted the blood of Jesus that has and is transforming us.
Sometimes it is hard to avoid the clique mentality when we have something in common with one group of people and not another but God did it. God is self-sufficient. He does not need anyone else. He has nothing in common with us. We have nothing to contribute to the Godhead. The Father, Son and Spirit don't need us. Yet, our Father reached out to us. Jesus left his place in that group to come and get us; to bring us into the group; to include us. Then he told us to go and do like-wise.
So, now we are to make the most out of every opportunity. We are to be wise toward those who are not part of the Body of Christ. They are the reason we are still here and Jesus told us to go to them. Avoid the clique mentality and reach out to someone today.