John Owen was an English Nonconformist church leader, theologian, and academic administrator at the University of Oxford. He was chosen to preach to parliament on the day after the execution of King Charles I, and succeeded in fulfilling his task without directly mentioning that event. Another sermon, a plea for sincerity of religion in high places, won not only the thanks of parliament but the friendship of Oliver Cromwell, who took Owen to Ireland as his chaplain, that he might regulate the affairs of Trinity College, Dublin. He pleaded with the House of Commons for the religious needs of Ireland as some years earlier he had pleaded for those of Wales. In March 1651, Cromwell, as Chancellor of Oxford University, gave him the deanery of Christ Church Cathedral, Oxford, and made him Vice-Chancellor of Oxford University in September 1652. During his eight years of official Oxford life Owen showed himself a firm disciplinarian, thorough in his methods, though, as John Locke testifies, the Aristotelian traditions in education underwent no change. While little encouragement was given to a spirit of free inquiry, Puritanism at Oxford was not simply an attempt to force education and culture into "the leaden moulds of Calvinistic theology." Owen, unlike many of his contemporaries, was more interested in the New Testament than in the Old. During his Oxford years he wrote Justitia Divina (1653), an exposition of the dogma that God cannot forgive sin without an atonement; Communion with God (1657), Doctrine of the Saints' Perseverance (1654), his final attack on Arminianism; Vindiciae Evangelicae, a treatise written by order of the Council of State against Socinianism as expounded by John Biddle; On the Mortification of Sin in Believers (1656), an introspective and analytic work; Schism (1657), one of the most readable of all his writings; Of Temptation (1658), an attempt to recall Puritanism to its cardinal spiritual attitude from the jarring anarchy of sectarianism and the pharisaism which had followed on popularity and threatened to destroy the early simplicity.