dont know how much this repeats the article; didnt read it. but the tldr is that: anti-catholicism starts out as a constitutive element in english republicanism*.
the act of supremacy and broader english reformation effectively collapsed religion, or at least ecclesiology, into politics. in early modern england, what we’d identify as someone’s position on the left-right spectrum was determined by their stance on matters theological/ecclesiastical. another way of saying it is that politics and political thought werent ultimately concerned with the ins and outs of policy, it was about attuning the temporal sphere to be in (more or less) perfect accordance with divine command and creation. so theres a monarchist strain of thought on the right exemplified in e.g. Hooker that, at its extreme, tends to absolutism e.g. Filmer. this is the strain thats the de facto court ideology and is interested in preserving (some of) the hierarchical makeup of the old late medieval church.
the strand on the left is the one that thought there was still plenty of reforming to do. the moderate wing is composed of calvinizing puritans who wanted a more presbyterian form of church polity. during the civil war (a republican/puritan victory, at least initially), theres a groundswell of a more radical wing of diggers, levellers, quakers and whatnot that are even more staunchly egalitarian; these guys are pretty much always peripheral though. anti-monarchist thought is stamped onto these guys so thoroughly that it welds really neatly with the good old anti-papalism and anti-clerisy thought that all protestants share. and that takes form (really, form
s) over the longue duree.
theres also an impulse -latitudinarianism- that gains steam throughout the 17th century towards a deflation of the importance of strict orthodox bonafides in order to receive inclusion into the anglican communion, and, a fortiori, politics. even as this more ‘liberalizing’ tendency becomes characteristic of the anglican church, the limit case for inclusion, now into a citizenry rather than a church polity, remains Catholicism. the arguments milton gives in the areopagitica and locke gives in the second treatise of government go something like: a citizen of a liberal polity cant serve a foreign master (the nation-state prong) and Rome’s ecclesiastical hierarchy vitiates the construction of a liberal citizen(ry) (the egalitarian prong). plus a whole bunch of denigration of the moral character of practising catholics -that theyre stupid, subservient, or superstitious.
puritan republicanism morphs into liberal whiggery after the restoration, and the anti-catholic elements largely stay put throughout the period leading up to the reform acts of the 1830s. like i said, its in milton and locke; its also in sidney, gordon & trenchard, and (im guessing, havent read it myself) in blackstone too. and these especially are the guys that the generation of madison/jefferson/adams were reading when they were formulating their own liberalism republicanisms.
on the catholic side of things, the episcopacy was very much not reconciled to mass, partisan politics until sometime around vatican ii. the ‘integralism’ debate and all the whinging about ‘modernism’ throughout the long nineteenth century was indicative of an anxiety over the increasingly slim chances of a return to a confessional model of european polity. it was becoming more and more clear that the object of state coercion was narrowing (expanding?
) to exclude its use to police the goodness of actions.**
so you still see both anxieties play out regularly in anglophone countries: non-catholics viewing catholics as subversives; catholics being conflicted between the moral vision of their church and the integrity of their liberal polity.
*really fraught term, only using it cause using ‘liberalism’ would be an even worse route to go down. for this post you can just read ‘republic’ it as the term that contrasts with ‘monarchy’
**let me emphasize -in political thought only. liberals in actual practice have absolutely used state coercion to impose ‘morals’, or whatever, on their constituents.