De Controversiis I

In this Theological treatise St. Robert Bellarmine takes on Protestant as well as Greek Orthodox objections to the Papacy in five books. In the first, he argues that Christ established the Primacy of Peter by means of an Ecclesiastical Monarchy, why it is fitting that the Church's government should be a monarchy; Exegetical Commentary on the Lord's words in Matthew 16 and John 21, along with copious Patristic testimony.
In Book 2 is whether Peter has successors in the Ecclesiastical Monarchy, wherein Bellarmine defends the Church's position on the true history of Peter; that Peter truly went to Rome; that Peter was truly a Bishop there.
In Book 3 Bellarmine shows the Pope is not Antichrist.
In Book 4, Bellarmine argues why the Pope is infallible when he defines a doctrine on faith and morals and proceeds to defend Popes whom Protestants and others argued had erred while defining faith.
In book 5, Bellarmine takes up the question of the Popes' power in civil affairs.