In spite of his Calvinistic opinions, he maintained that to acknowledge the errors which had arisen in the Catholic Church did not necessarily imply disbelief in her catholicity, and that the Church of England having repudiated these errors should not deny the claims of the Roman Catholic Church on that account. This view commended itself to Charles I and his episcopal advisers; even if Hall, with John Davenant and Thomas Morton, was considered a likely die-hard by Richard Montagu if it ever came to reunification with the Catholic Church. At the same time, Archbishop Laud sent spies into Hall's diocese to report on the Calvinistic tendencies of the bishop and his lenience to the Puritan and low church clergy. Hall gradually took up an anti-Laudian, but also anti-Presbyterian position, while remaining a Protestant eirenicist in co-operation with John Dury and concerned with continental Europe.