Next year he followed the example of Henry of Navarre by abjuring the Protestant faith.
After a royalist insurrection in 1655, a proclamation was issued announcing that persons suspected of Roman Catholicism would be required to take an oath abjuring the papal authority and transubstantiation.
Abjuring pomps and vanities, its citizens observed the ascetic regime of the cloister; half the year was devoted to abstinence and few dared to eat meat on the fasts ordained by Savonarola.
In May he had charge of the bill for securing the Protestant succession; he took part in the impeachment of the Whig lords for their conduct concerning the Partition treaties, and opposed the oath abjuring the Pretender.
He "very violently" opposed the oath abjuring the house of Stuart, now sought to be imposed by the republican faction on the parliament, and absented himself from the House for ten days, to avoid, it was said, any responsibility for the bill.