A proof of the rapid progress of Bartholomew may be seen in his trial. Fray Michel de St. Martin, a Dominican monk, and a professor in the same college at Valladolid, denounced him to the holy office, in 1530, deposing that, two or three years before, he had had several conversations with Carranza, on subjects concerning his conscience; that he had remarked that he limited the power of the Pope, relating to the ecclesiastical ceremonies; and that he had reprimanded him for so erroneous an opinion. Carranza was also denounced in 1530, by Fray Juan de Villamartin, as having been the ardent defender of Erasmus, even on the subject of the sacrament of penance, and the frequent confession of persons who are only in a state of venial sin; that having opposed to him the example of St. Jerome, he maintained that it was impossible to support the fact by the authority of any respectable ecclesiastical historian; that Carranza also said Erasmus ought not to be contemned, for saying that the Apocalypse was not the work of St. John the Evangelist, but of another priest, who bore the same name.
These denunciations were not made use of until the instruction of the trial of the archbishop was far advanced, when every method was employed to find materials for accusations; the denunciations and suspended trials were then looked over, and those above-mentioned were found. They were noted as declarations of witnesses, under the numbers ninety-four and ninety-five; while, according to the dates, they ought to have been the first.
As these denunciations were not known out of the holy office, the rector and counsellors of the College of St. Gregory de Valladolid presented Carranza, in 1530, as a professor of philosophy; in 1534 he was appointed professor of theology, and soon after a qualifier to the holy office of Valladolid. In 1539 he was sent to Rome, to attend a general chapter of his order, where he was chosen to maintain the theses, which were only confided to persons capable of performing their duty well: the talents he displayed in these exercises obtained him the rank of Doctor and Master of Theology; and Paul III. permitted him to read prohibited books.
On his return to Spain, he professed theology, with the greatest success, in his College of St. Gregory. The harvest having entirely failed in the mountains of Leon and Santander in 1540, the inhabitants went to Valladolid in great numbers. Carranza not only maintained forty of these poor people in his college, but sold his books to assist others in the city, only retaining his Bible, and the Summary of St. Thomas. During this period he was continually occupied, either at the holy office as a qualifier, or at home in censuring books sent to him by the Supreme Council, or in preaching sermons at the auto-da-fé.
In the same year, 1540, Carranza was appointed Bishop of Cuzco, but he refused to go to South America, except as a preacher of the gospel. In 1544, Carranza was sent to the Council of Trent, as theologian to Charles V. He remained there three years, and it was there that Cardinal Pacheco (dean of the Spanish prelates who attended at the council) engaged him to preach on justification before the Fathers. In 1546, he published at Rome one of his works, called The Summary of Councils; and another at Venice, of Theological Controversies. In 1547 he published a treatise On the Residence of Bishops, which created him many enemies, and which was attacked by Fray Ambrose Caterino, and defended by Fray Dominic de Soto, both Dominicans.
On his return to Spain, in 1548, he refused the appointment of confessor to Philip II., then prince of the Asturias, and in 1549 declined accepting the bishopric of the Canaries. He was elected in the same year prior of the Dominicans of Palencia, which he accepted. In 1550 he was made provincial of the Convents of Castile, and visited his province.
The Council of Trent being again convoked in 1651, Carranza was commanded by the emperor to attend it, and furnished with full powers by the Cardinal Archbishop of Toledo; he assisted at the different assemblies until 1552, when he was suspended the second time. Among the different commissions confided to him, was that of preparing an Index. On his return to Spain, the period of his provincialship had expired, and he re-entered his College of St. Gregory of Valladolid.
The alliance between Philip II. and Mary, Queen of England, being fixed, Fray Bartholomew, in 1554, went to England in order to assist Cardinal Pole in preparing the kingdom to return to the Catholic faith. Carranza passed the greatest part of his time in preaching, and succeeded in converting a great number of heretics. When the king left England to go to Brussels, Carranza remained with the queen, to whom he was useful in supporting the Catholic doctrine in the universities, and arranging other affairs of the greatest importance. He revised, by the order of Cardinal Pole, the canons which had been decreed by a national council, and caused several obstinate heretics to be punished, particularly Thomas Cranmer, Archbishop of Canterbury, and Martin Bucer; his zeal often exposed him to great danger.
In 1557 he went to Flanders, where he caused all books infected with the heresy of Luther to be burnt. He did the same at Frankfort, and also informed the king that many of these books were introduced into Spain by way of Aragon. Philip, in consequence, gave the necessary orders to the inquisitor-general to intercept these works. In order to render this measure more effectual, Carranza drew up a list of suspected Spaniards who had fled to Germany and Flanders. The original copy of this list was found among his papers when he was arrested.
On the death of Cardinal Siliceo, Archbishop of Toledo, the king appointed Carranza to succeed him; he however refused to accept the dignity, and named Don Gaspard de Zuñiga y Avellanada, Bishop of Segovia, Don Francis de Navarra, Bishop of Badajoz, and Don Alphonso de Castro, a Franciscan, as more worthy of the king's choice than himself. He persisted in his refusal, until the king commanded him on his allegiance to accept the archbishopric: the original of this royal order was also found among the papers of Carranza. Paul IV. dispensed with the usual formalities; he was preconised in a full consistory on the 16th December, 1557, and his bulls were expedited. Pedro de Merida, canon of Palencia, administrated until the arrival of the archbishop. The Inquisition of Valladolid afterwards prosecuted him for some letters which he had written to Carranza, and which were found among his papers; he was also implicated by Fray Dominic de Roxas, and by other accomplices of Dr. Cazalla.