Until 1589, Bellarmine was occupied as professor of theology. After the murder in that year of Henry III of France, Pope Sixtus V sent Enrico Caetani as legate to Paris[2] to negotiate with the Catholic League of France, and chose Bellarmine to accompany him as theologian.[3] He was in the city during its siege by Henry of Navarre.

The next pope, Clement VIII, set great store by him. He was made rector of the Roman College in 1592, examiner of bishops in 1598, and cardinal in 1599. Immediately after his appointment as Cardinal, Pope Clement made him a Cardinal Inquisitor, in which capacity he served as one of the judges at the trial of Giordano Bruno, and concurred in the decision which condemned Bruno to be burned at the stake as a heretic. [4]

The Galileo case
In 1616, on the orders of Paul V, Bellarmine summoned Galileo, notified him of a forthcoming decree of the Congregation of the Index condemning the Copernican doctrine of the mobility of the Earth and the immobility of the Sun, and ordered him to abandon it.[5] Galileo agreed.[6] When Galileo later complained of rumors to the effect that he had been forced to abjure and do penance, Bellarmine wrote out a certificate denying the rumors, stating that Galileo had merely been notified of the decree and informed that, as a consequence of it, the Copernican doctrine could not be "defended or held".[7] Cardinal Bellarmine was himself ambiguous about heliocentrism, personally noting that further research had to be done to confirm or condemn it.[citation needed] (In 1633, Galileo would again be called before the Inquisition in this matter.)

Dogmatics
Main article: Disputationes
From his research grew his Disputationes de controversiis christianae fidei (also called Disputationes), first published at Ingolstadt in 1581–1593. This major work was the earliest attempt to systematize the various religious controversies of the time. Bellarmine devoted eleven years to it while at the Roman College. The first volume of the Disputationes treats of the Word of God, of Christ, and of the Pope; the second of the authority of ecumenical councils, and of the Church, whether militant, expectant, or triumphant; the third of the sacraments; and the fourth of Divine grace, free will, justification, and good works.[citation needed