Such an offer was in exact accordance with his own wishes. But he had no intention of becoming king of Sweden merely to remain a tool in the hands of the spiritual and lay lords as the kings of Denmark had remained. Determined in his own mind to make himself absolute ruler of Sweden by crushing the bishops and barons, he recognised that Luther's teaching, with which he was familiar owing to his stay at Lubeck, held out good hopes for the success of such a project. The warm attachment of the Bishop of Upsala for the Danish faction had weakened the devotion of the people to the Church, and had prepared the way for the change which Gustavus contemplated. Some of the Swedish ecclesiastics, notably the brothers Olaf and Laurence Peterson, both students of Wittenberg, the former a well-known preacher at Stockholm, the latter a professor at Upsala, were strongly Lutheran in their tendencies, and were ready to assist the king. Though in his letters to Rome and in his public pronouncements Gustavus professed himself to be a sincere son of the Church, anxious only to prevent at all costs the spread of Lutheranism in his dominions, he was taking steps secretly to encourage his Lutheran supporters and to rid himself of the bishops and members of the religious orders from whom he feared serious opposition. As was done elsewhere, he arranged for a public disputation at which Olaf Peterson undertook to defend the main principles advocated by Luther, but the results of the controversy were not so satisfactory for his party as he had anticipated.
Gustavus now threw off the mask of hypocrisy, and came forward boldly as the champion of the new religion. He removed those bishops who were most outspoken in their opposition, banished the Dominicans who stood loyal to Rome, and tried to force the clergy to accept the change.
Anxious to enrich his treasury by confiscating the wealth of the Church he scattered broadcast Luther's pamphlet on the confiscation of ecclesiastical property, and engaged the professors of the University of Upsala to use their efforts to defend and popularise the views it contained. A commission was appointed to make an inventory of the goods of the bishops and religious institutions and to induce the monasteries to make a voluntary surrender of their property. By means of threats and promises the commissioners secured compliance with the wishes of the king in some districts, though in others, as for example in Upsala, the arrival of the commission led to scenes of the greatest violence and commotion. More severe measures were necessary to overawe the people, and Gustavus was not a man to hesitate at anything likely to promote the success of his plans. Bishop Jakobson and some of the clergy were arrested, and after having been treated with every species of indignity were put to death (1527).
In this year, 1527, a national Diet was held at Vesteras principally for the discussion of the religious difficulties that had arisen. Both parties, the supporters of the old and of the new, mustered their forces for a final conflict. Gustavus took the side of the so-called reformers, and proposed the measures which he maintained were required both in the interests of religion and of the public weal. The Catholic party were slightly in the majority and refused to assent to these proposals. Gustavus, though disappointed at the result, did not despair. He announced to the Diet that in view of its refusal to agree to his terms he could undertake no longer the government and defence of the country. A measure such as this, calculated to lead to anarchy and possibly to a new subjugation of the country by Denmark, was regarded by both sides as a national disaster, and secured for the king the support of the waverers. The masses of the people were alarmed lest their opposition might lead to the restoration of Danish tyranny, while the support of the nobles was secured by the publication of a decree authorising them to resume possession of all property handed over by their ancestors to religious institutions for the last eighty years. The remainder of the possessions of the Church were appropriated for the royal treasury. The king now issued a proclamation in favour of the new religion, insisted on the adoption of a liturgy in the vulgar tongue, and abolished clerical celibacy. At the National Assembly of Orebro (1529) the Catholic religion was abolished in favour of Lutheranism, and two years later Laurence Peterson was appointed first Lutheran Archbishop of Upsala.
