The present study is an analysis of covenantal identity and ritual boundaries based on texts ranging from the Old Testament, the Book of Jubilees, the Dead Sea Scrolls to the New Testament. A pattern of interdependence between group identity and boundary marks is traced, and the following thesis is examined: a community's identity is reflected in boundary marks, and ritual boundaries reflect a corporate identity. By using this general principle to interpret biblical and intertestamental material a pattern emerges: when identity is defined in ethnic categories, boundaries are wide, national boundaries, when identity is defined in particularistic categories, such as priestly purity, boundaries are narrow markers of purity. When identity is changed, boundaries change. Having chosen the Old Testament covenant concept as a term for ecclesiological identity the writer demonstrates that covenantal identity changes in Palestinian Judaism not least because it narrows down and builds on the principle of law. As a result of this, ritual boundaries become narrow marks of law observance. When such an interpretation is challenged by Paul covenant is redefined. The Old Testament and intertestamental pattern of interdependence helps to explain that Paul reinterprets covenant and why old ritual boundaries are replaced. Since for Paul identity is grounded in faith in the one Christ, the ecclesiological boundary is no longer an exclusive covenant rite, such as circumcision, rather baptism is, since it serves as a rite of identification with Christ and a mark of possession of the Spirit. This reflects a radical change in ecclesiology. When Christian baptism is the boundary marker that reflects unity with Christ and serves as an inclusive rite; it simultaneously becomes the only symbol for incorporation in the one church.