Today, the seventh day of the Week of Prayer for Christian Unity, is the feast day of St. Francis de Sales, (1567-1622), bishop of Geneva and Doctor of the Church.
In 1594 he volunteered to go to Le Chablais, south of Geneva, where the population had become Calvinist and separated from the Catholic Church. The encyclopedia article explains St. Francis' subsequent activity:
He journeyed through the entire district, preaching constantly; by dint of zeal, learning, kindness and holiness he at last obtained a hearing. He then settled in Thonon, the chief town. He confuted the preachers sent by Geneva to oppose him; he converted the syndic and several prominent Calvinists. At the request of the pope, Clement VIII, he went to Geneva to interview Theodore Beza, who was called the Patriarch of the Reformation. The latter received him kindly and seemed for a while shaken, but had not the courage to take the final steps.
Through his work in this region over the course of four years (from 1594 to 1598), 72,000 Calvinists were brought back into the Catholic Church. When he initially went from house to house to talk with the Calvinists, they refused to talk with him or even listen to him. So he started writing pamphlets, and slipping them under doors in the villages and towns. Those pamphlets have been collected into the book now published under the title: The Catholic Controversy: St. Francis de Sales' Defense of the Faith.
One of the more important points in these pamphlets is that the Church comes from the Apostles, as the Apostles come from Christ, and as Christ comes from the Father. The Father sent the Son. The Son authorized and commissioned the Apostles. The Apostles authorized and commissioned the bishops. And these bishops authorized and commissioned bishops. This is a top-down transmission of divine authority and mission, from the Father to Christ, from Christ to the Apostles, and from the Apostles to the bishops they ordained. Only those persons authorized and sent by the Apostles should be received by Christians as rightful shepherds, and thus only those authorized and sent by the bishops sent by the Apostles should be received by Christians as rightful shepherds. We should not follow those who are self-sent, or self-appointed, for such persons are not authorized by Christ to shepherd the Lord's sheep. Anyone can claim to be authorized, but only those who have been authorized by those whom the Apostles authorized are actually authorized. The Calvinists were following self-appointed men who were not authorized to speak for the Church. St. Francis taught that these men had not entered the sheepfold by the door, but were climbing in some other way.
St. Francis explained that the unity of the Church derives directly from the unity of Christ Himself, through a continuous organic relation to the incarnate Christ, by holding to the shepherds who have authorization from the Apostles. Just as an organism grows, so by apostolic succession the Church retains within itself the unity it received directly from the incarnate Christ, its Head. "We are to grow up in all aspects into Him, who is the head, even Christ from whom the whole body, being fitted and held together by that which every joint supplies ...." (Ephesians 4:16)
The bust at right is located on the west side of the Saint Louis Cathedral Basilica.