Religious issues were of the utmost importance to the overwhelming majority of lords: bills concerned with the Church of England or nonconformists brought them flocking to Westminster. Particularly controversial pieces of legislation, such as the 1662 Uniformity Bill and the Conventicle Bill of 1664, witnessed attendances in excess of eighty lords per sitting. A considerable variety of religious views existed within the nobility, with few peers being either sceptics or unbelievers. The vast majority of lords conformed to the rites and ceremonies of the established church, but a tiny minority consisting of Protestant nonconformists and Catholics did not.

Categorising peers according to their religious beliefs is fraught with difficulties. Only a handful of peers have left records of their opinions in letters, commonplace books and diaries. For many the only surviving evidence of their religious views is parliamentary speeches, division lists and protests. Even here the evidence is sparse: there was no noble equivalent of a Grey or a Milward diligently scribbling down speeches. Several complete division lists survive from the 1670s, whilst none on religious subjects exists for the 1660s. Of course political actions did not necessarily accord with a lord's private religious beliefs. Despite his ultra-Anglican views, the earl of Bridgewater voted with his Country party friends for an amendment favourable to Protestant dissenters in a 1679 bill for removing papists from London. Others holding court posts, like the duke of Ormond and the king's own brother, the duke of York, had been persuaded by Clarendon to support amendments to religious bills in 1662, despite having private reservations.