In 1604 James drew up for Catholics an oath of allegiance which not only denied the power of the Pope to depose kings, but declared that such a claim was heretical, impious and damnable. It was condemned by Paul V, but the Archpriest Blackwell publicly announced that notwithstanding the condemnation, the oath might be conscientiously taken by any English Catholic, and he accepted it himself before the Commissioners of Lambeth. Bellarmine and Persons wrote long expostulations to him, but without avail. He was finally deposed from office, and Birkhead took his place as archpriest. "This measure," says Lingard, "was productive of a deep and long-continued schism in the Catholic body. The greater number, swayed by the authority of the new Archpriest and of the Jesuit missionaries, looked upon the oath as a denial of their religion; but, on the other hand, many preferring to be satisfied with the arguments of Blackwell and his advocates, cheerfully took it, when it was offered, and thus freed themselves from the severe penalties to which they would have been subject by the refusal" (op. cit., IX, 77).
Now came the disaster. Irritated beyond measure by the treachery and the tyranny of King James I, a number of Catholic gentlemen, some of them recent converts, formed a plot to blow up the House of Parliament and so get rid of king, lords and commons by one blow.
While the plans were being laid, some of the conspirators began to doubt about their right to involve so many innocent people in the wholesale ruin that must result from this terrible crime. To settle their scruples, Catesby, the chief plotter, proposed a supposititious case to Father Garnet, the Jesuit provincial. "I am going to join the army of the Archduke on the Continent," he said, "and I may be ordered, for example, to blow up a mine in order to destroy the enemy. Can I do so, even if a number of innocent persons are killed?" The answer of course was in the affirmative, and then Catesby made haste to assure his friends that they could proceed in their work with a safe conscience. But as time wore on, he was noticed by his friends to be habitually excited, very often absent from home, and apparently not preparing to go abroad, as he had said he intended to do. Hence, suspicion was aroused, and Garnet, having received some vague hints of the conspiracy, took occasion at Catesby's own table, to inculcate on his host the necessity of submitting meekly to the persecution then going on. Whereupon Catesby burst out in a rage: "It is to you and such as you," he exclaimed, "that we owe our present calamities. This doctrine of non-resistance makes us slaves. No priest or pontiff can deprive a man of the right to repel injustice." Garnet, alarmed at this utterance, immediately wrote to his superior in Rome, and in due time received two letters, one from the General, the other from the Pope, putting him under strict orders to do all in his power to prevent any attempt against the State. These letters were shown to Catesby, but he protested that they were written on wrong information, and he volunteered to send a special messenger to Rome to put before the authorities there the true state of things. This promise satisfied Garnet, and he felt sure the matter was disposed of, at least, for a time.