Some churches are formed by presbyteries. Some are formed by dioceses. However, churches that are independent of these forms of government are formed by covenant with like-minded believers. Although there is no mention of a church covenant in Scripture, all local churches are formed by covenant. There are two facets to this covenanting. First, a church consists of those who are in the New Covenant -- that is, they are believers. Second, a church is formed by those who decide to covenant -- they agree to walk together and belong to one another.
John Piper said, “a church without a covenant is like a marriage without vows.” Some churches define membership by baptism, some by adherence to a statement of their faith. We define membership by household in terms of a written covenant. You can read our church covenant here.