It is important to understand the role of Catholicism in answering this question. To the Protestant world during the period, Catholicism was the ultimate symbol of absolutism and oppression. Many were fearful of the absolute monarchies, particularly those of Catholic France and Spain. So when Charles I began to show Catholic tendancies, such as his conversion to Arminianism (a type of protestantism that uses Catholic-style ceremonies) and the establishment of Charles's Personal Rule (absolute rule) in 1629, many English and Scottish protestants were understandably concerned, none more so than the puritans. Even so, this wasn't enough for anti-monarchist sentiment, even after the 'First' English Civil War (1642-46) where parliament fought the king in open battle. Many parliamentarians only wanted a constitutional monarchy with limits on Charles I's power. Obviously by Charles's execution in 1649 that had changed entirely thanks to the role of the New Model Army, however that is a different question entirely. So when Cromwell and the puritan-dominated parliament (now called the Rump after a coup named Pride's Purge) sent Charlie's head rolling, he was seen by many as a liberator; someone who put down a tyrannical king who was intent on establishing a Catholic absolute monarchy, and oppressing Protestant England and Scotland. Clearly it is massively debateable whether he was a liberator or not, especially after his actions in Ireland. He is seen by some as theocratic due to his strict opposition to Catholicism for the reasons stated above, which could be comparable to post 1979 Iran, although that level of theocracy could be said for pretty much every other European country during the 1650s aswell. And it could also be argued that Cromwell wasn't massively theocratic, as he personally wanted religious tolerance amongst all the different types of protestants, and the theocratic element was more down to the numerous parliaments of the period. They were mostly made up of puritans or more conservative (more pro-monarchy) protestants, neither of whom particularly wanted religious tolerance.