A parish is a portion of a Diocese under the authority of a priest legitimately appointed to secure in virtue of his office for the faithful dwelling therein. The faithful are called parishioners. To form a parish there must be a certain body of the faithful over whom pastoral authority is exercised; the ordinary manner of determining them is by assigning a territory subject to the exclusive jurisdiction of the Parish Priest. The faithful become parishioners by acquiring a domicile or a quasi-domicile within the territory, or by simply living in it.
Sacred Heart of Jesus – Roan Section 1