It is also taught among us that one holy Christian church will be and remain focever. This is the assembly of all believers [or "saints"] among whom the Gospel is preached in its purity and the holy sacraments are administered according to the Gospel. For it is sufficient [satis est] for the true unity of the Christian church that the Gospel be preached in conformity with a pure understanding of it and that the sacraments be administered in accordance with the divine Word [or, "are administered rightly"]. It is not necessary for the true unity of the Christian church that ceremonies, instituted by men, should be observed uniformly in all places. It is as Paul says in Eph. 4:4,5, "There is one body and one Spirit, just as you were called to the one hope that belongs to your call, one Lord, one faith, one baptism. "1
Johnson, Maxwell E., "Salis est: Ecumenical Catalyst or Narrow Reductionism?" (2003). Institute of Liturgical Studies Occasional Papers. Paper 102.