Today, September 17, is the memorial of St. Robert Bellarmine, who died 386 years ago today (October 4, 1542 - September 17, 1621). He was given the title "Hammer of heresies" by Pope Benedict XV. He is also now one of the thirty-three "Doctors of the Church". In an age when 'heresy' is often reduced to "any interpretation of Scripture that doesn't line up with my straight-forward non-interpretation of what the Scripture itself says", St. Bellarmine shows that heresy is such only in relation to the Church's magisterium. Since doctrinal unity is an important step in achieving full visible unity, understanding what is the principled distinction between orthodoxy and heresy is essential for Church unity. His Disputationes de controversiis christianae fidei is the standard and still unmatched response of the Catholic Church to certain Protestant errors. The contemporary Protestant leaders recognized the significance of this work, and set up academic chairs devoted exclusively to attempting to reply to it. St. Francis de Sales drew extensively from it in his discussions with the Calvinists in Geneva. To read more about St. Bellarmine, see here and here, and here.
St. Bellarmine's fifteen marks of the Church are as follows: (HT: DOTCC)
(1) The Church's Name, Catholic, universal, and world wide, and not confined to any particular nation or people.
(2) Antiquity, in tracing her ancestry directly to Jesus Christ.
(3) Constant Duration, in lasting substantially unchanged for so many centuries.
(4) Extensiveness, in the number of her loyal members.
(5) Episcopal Succession, of her Bishops from the first Apostles at the Last Supper to the present hierarchy.
(6) Doctrinal Agreement, of her doctrine with the teaching of the ancient Church.
(7) Union, of her members among themselves, and with their visible head, the Roman Pontiff.
(8) Holiness, of doctrine in reflecting the sanctity of GOD.
(9) Efficacy, of doctrine in its power to sanctify believers, and inspire them to great moral achievement.
(10) Holiness of Life, of the Church's representative writers and defenders.
(11) The glory of Miracles, worked in the Church and under the Church's auspices.
(12) The gift of Prophesy found among the Church's saints and spokesmen.
(13) The Opposition that the Church arouses among those who attack her on the very grounds that Christ was opposed by His enemies.
(14) The Unhappy End, of those who fight against her.
(15) The Temporal Peace and Earthly Happiness of those who live by the Church's teaching and defend her interests.
St. Robert Bellarmine, please pray for us that we would all be united in doctrinal purity and in peace and unity under the successor of St. Peter, that the Bride of Christ might shine with beauty and radiance at the return of the Bridegroom.
"Let unity, the greatest good of all goods, be your preoccupation." - St. Ignatius of Antioch (Letter to St. Polycarp)