Some churches ask their members to sign a covenant. A covenant is what we would use to describe the vows between a husband and his wife, and between God and his people. Signing a covenant helps prospective members understand what it means to be a part of the church. The member covenant is not a legal document or some sort of cultic rite. It is an affirmation, an agreement, and a source of accountability for both the church and its individual members. Here is a sample of a membership covenant used by Redlands CRC.
Source: Redlands Christian Reformed Church