High Quality Content by WIKIPEDIA articles! The Roman Catholic Diocese of Oakland is an ecclesiastical territory or diocese of the Roman Catholic Church in Northern California. The diocese comprises Alameda and Contra Costa Counties in the San Francisco Bay Area. The Cathedral of Christ the Light serves as the bishop's seat, replacing the Cathedral of Saint Francis de Sales which was demolished after the Loma Prieta Earthquake of 1989. Once a part of the Archdiocese of San Francisco, the Diocese of Oakland remains a suffragan of the ecclesiastical province of San Francisco. Its fellow suffragans include the dioceses of Honolulu, Las Vegas, Reno, Sacramento, Salt Lake City, San Jose, Santa Rosa and Stockton.