St. Robert Bellarmine's defense of Papal authority has no equal. He wrote volumes concerning the role of the vicar of Christ here on earth, the Pope. It was the Popes of his time that determined Cardinal Bellarmine's calling was the apologetic defense of the Catholic Faith, in particular the Divine Rights given to the Pope.
Here is a smidgen of his great defense of the Pope.
But we teach that there is only one Church, ant not two, and that the one true Church is the assembly of men bound together by the profession of the same Christian faith and by the communion of the same sacraments, under the rule of legitimate pastors, and especially of the one vicar of Christ on earth, the Roman pontiff.
- Cardinal Robert Bellarmine, De Ecclesia Militante