Although Cromwell had abolished the monarchy and had King Charles I executed, as so-called Lord Protector he achieved a level of power that made him a king in all but name. Indeed at one point he seriously considered having himself crowned as king, but thought better of it. Cromwell had come to see himself as chosen by God to lead the country, and that he, and he alone, had what it took to bring much-needed stability to a nation still riven by deep religious and political divisions.
As such, Cromwell became isolated from both his fellow countrymen and from many of the Parliamentarians who had fought alongside him against King Charles I during the Civil Wars. Cromwell's divine sense of mission led to conflicts with Parliament strangely reminiscent of those that had taken place under Charles I. Eventually, Cromwell angrily dissolved the so-called Rump Parliament in what was effectively a military coup. It is ironic indeed that someone who fought so valiantly for the rights of Parliament against the monarchy should have treated the institution with the kind of high-handed contempt worthy of Charles I himself.
Though a deeply devout Christian, Cromwell resisted the call of many of his fellow Puritans for the establishment of a national church on Presbyterian lines. He was an Independent, that is to say someone who believed that individual congregations should determine their own forms of worship—so long as they were Protestant, of course.
In terms of personality, Charles II couldn't really have been more different to Cromwell. Aptly nicknamed "The Merry Monarch" he was a rather shallow, easygoing man who enjoyed the company of women, by whom he sired numerous illegitimate offspring. Charles had as little time for Parliament as his late father, but proved himself more skillful in dealing with their numerous grievances. Charles, in common with all the Stuart kings, had aspirations to be an absolute monarch, and cast envious eyes across the English Channel at his French cousin, Louis XIV. Indeed, Charles was able to rule without Parliament for the last four years of his life thanks to secret payments from Louis.
Under Charles, the Church of England was restored to the position of prominence it had lost under Cromwell. At the same time, religious uniformity was imposed throughout the realm. The Act of Uniformity (1662) and subsequent measures systematically excluded Puritans and other non-conformists from public life, and made it hard for them to practice their faith openly. Though it should be said that Charles was personally quite tolerant when it came to religious matters; his church policy was practical, not ideological, chiefly motivated by the necessity of establishing good order in the kingdom.
Charles's mother, wife and brother were Roman Catholics. (It is generally accepted that Charles himself converted to Catholicism on his death-bed). However, official persecution against Catholics remained in force throughout his reign. Again, this was for political reasons, as Charles shrewdly realized that any relaxation of restrictions on Catholics would be deeply unpopular and almost certainly undermine his throne. This was a lesson lost on his brother, James, Duke of York, who became—to date—Britain's last Catholic monarch upon Charles II's death in 1685.
Odd as it might seem, Oliver Cromwell, who ruled as Lord Protector after the execution of Charles I, was more absolutist and autocratic than Charles II; in fact he bore more resemblance to Charles I than he would likely have admitted. Cromwell was a dedicated Puritan and at times idealistic to a fault. He was determined that no one, not even Parliament, would prevent him from instituting the reforms which he considered necessary. The "Rump Parliament" had prepared a Constitution known as the "Instrument of Government" in 1653 which ostensibly created the office of Lord Protector; however when Parliament refused to dissolve itself, Cromwell destroyed the Constitution and ruled under virtual Martial Law. He was able to do so as the Puritan Army from the Civil War were loyal to him, and he was thus able to create a virtual military dictatorship. As a result, he imposed taxes without the consent of Parliament, closed theaters, prohibited sporting events, and even censored the Press. He was so unpopular that he found it necessary to wear armor under his clothing, and travel through London by circuitous routes for his own safety.
Charles II, restored in 1661 after Cromwell's death, was in his own words determined "not to set out on my travels again." Whereas Cromwell had been idealistic, Charles proved to be conciliatory. He was determined to cooperate with Parliament by whatever means, and agreed to summon Parliament frequently. He also agreed to not impose taxes without Parliament's consent. Whereas Cromwell had been dour and uncooperative, Charles had a keen sense of humor and could be quite charming when he saw the need. Even so, Charles' reign was not altogether successful. Parliament was much more conservative than the King, a fact which led to continuing conflict over the proper relationship between King and Parliament. One interesting development in Charles' reign was the creation of a council of five advisers who were to act as liaisons between Charles and Parliament. The advisers were all members of Parliament, which indicated his intent to cooperate whenever possible. Interestingly, the first five advisers (Clifford, Arlington, Buckingham, Ashley-Cooper, and Lauderdale) became known as the "Cabal," based on the first initials of their names. This was the beginning of the Cabinet system of government in England.