Opinion of Oliver Cromwell

[The Mikado]

Genocidal maniac (sane, normal, blah blah).

Not sure about the maniac part.

Cromwell has a number of issues, even setting aside the elephant in the room that is Ireland. 

[The Mikado]

The claim that the Stuarts were instituting "tyranny" by attempting to allow a limited measure of religious freedom is something of a 17th-century mirror of the modern argument that allowing same-sex marriage is "tyranny." Complete with the role of "activist judges" replaced by "absolute monarchs."

Attempting to impose the Book of Common Prayer on Scotland was a "limited measure of religious freedom?" 

[The Mikado]

The claim that the Stuarts were instituting "tyranny" by attempting to allow a limited measure of religious freedom is something of a 17th-century mirror of the modern argument that allowing same-sex marriage is "tyranny." Complete with the role of "activist judges" replaced by "absolute monarchs."

Attempting to impose the Book of Common Prayer on Scotland was a "limited measure of religious freedom?" 

Yes, because unlike the Dissenters the Anglicans were not (or at least not nearly as much) in favor of running the country as a hellish theocracy where any deviationist religious views, or anything fun for that matter, was met by being tortured to death, as evidenced by their views on such matters as "we don't like your book, so let's go kill 300,000 people." If the Dissenters had their way we wouldn't have had Shakespeare.

I'm seriously drawing a blank at how imposing episcopacy and Anglican prayers on a deeply Calvinist Presbyterian Scotland to which those things were deeply hateful is an act of religious toleration and liberty.  I fail to see how William Laud's scheme to impose the Church of England upon a Scotland that was not at all ready to receive it, to the point of having Charles invade his own kingdom of Scotland at gunpoint to enforce this situation, has anything to do with toleration.

[The Mikado]

It's a false choice, given that Charles I was actively moving away from the de facto tolerance of Elizabeth I's reign and even his father's in attempting a more uniform and less varied church and in trying to extend that church's reach to Scotland, where it had never held sway before.  I don't see how you can interpret the monarchy's moves in the 1630s as anything other than a move against religious tolerance and diversity of tolerated opinion within the three kingdoms.

EDIT: You do remember that Charles called Parliament into session in order to vote him the money he needed to forcibly convert Scotland at gunpoint, right?

EDIT 2: I really don't get how anyone could look at the career of Charles I and go "Here's a friend of religious diversity."  Right from the beginning he was plotting with Bishop Laud to harmonize every Anglican Church and crush the regional diversity within it as an institution and to extend its hegemony north of the border into Scotland where it had never held sway before.  That's, like, the opposite of tolerance of religious diversity.

[The Mikado]

With regards to Ireland, it's pretty reasonable to say that the Protectorate was simply following the path that their predecessors had blazed out and their successors would continue.