Whether a person attends a church, cathedral or basilica, they are part of a congregation. This is the most important designation in any church. No matter what religion is practiced, being a member of a congregation is how people feel connected to the church and the other members. It signifies they have found a spiritual home where they can be a part of a family. For many people, this spiritual family is often the closest relationship they will have outside of their birth family.
Many congregations do expect their members to attend worship services on a regular basis. They are also expected to tithe a portion of their income to help support the church. Buildings and programs cannot be maintained without funds. While churches were not dependent on their congregations centuries ago, many no longer own vast tracts of land that was rented out to provide the church's income.