The Catholic Christian religion in Ireland had a long history of being independent, especially from Rome. Ireland was Catholic, but it was an indigenous form of Catholicism. In fact one of the reasons put forward for the English invasion in the 12th century was a directive from the Pope to 'reform' the Irish church and bring it under a more European model. It was only then that a diocesan model was introduced, and then not very successfully.

Ireland was a difficulty for the English invaders from the time of the first incursions in the late 12th century. The Anglo-Norman invaders assimilated into Irish society and spoke the Irish language, took up Irish customs and the Irish law system. The Statutes of Kilkenny in 1366 tried to redress this and attempted a form of segregation putting the native Irish culture outside of the law. The statutes imposed the English language and outlawed Irish culture, language, laws, even the game of hurling, but this had little effect.

The Irish church, like Irish society, remained decentralised and acted independently. For instance, during the reign of Henry VII it was the Irish bishops [in concert with the Irish parliament] who acted out of Irish interest and crowned Lambert Simnel of York King of England in Christ Church cathedral in Dublin. This enraged the Pope who ordered the Irish bishops to give allegiance to Henry VII. The order was largely ignored. This resulted in the imposition of Ponyings Law by Henry VII, a law which greatly reduced the power of the Irish Parliament and attempted to bring it under the control of Westminster. This in spite of the fact that no native Irish were permitted into the Irish parliament. It was a colonial parliament for those of English decent only.

There were numerous rebellions against the Norman English settler lands from native Irish Chieftains but the leading Norman families, the Butlers and the FitzGeralds essentially became integrated within Irish society. This made imposing English rule on Ireland - extracting taxes - a difficulty right up until the Reformation. In fact the so called 'ruling family', the FitzGeralds were so independent that Garret Mór FitzGerald, ostensibly the Lord Deputy, was under arrest at the time of the Reformation. He was summoned to London by Henry VIII in late 1533 to answer questions about his administration in Ireland. Shortly after arrival he was arrested. This enraged both native Irish and Anglo-Irish. Ireland was in turmoil and a FitzGerald led rebellion followed but ended in the arrest of and hanging of leading FitzGerald family members. In 1536 Henry ordered the Irish Parliament -many of whom had sided with the FitzGeralds - to recognise him as Head of the new Church. They did so, but it meant very little. The native Irish chieftains were not interested in what new laws or rules were coming from England. They continued to speak the Irish language, held to Irish customs and to the old Irish law system Brehon law. Very little changed. An emissary sent from Henry to oversee the Irish situation wrote to Henry that the native Irish culture was dominant and in control and that the 'English blood' of the original conquest was worn out.

It was against this background that any attempt to enforce or establish an English religion proved impossible. During future attempts, especially under Elizabeth I, vast Elizabethan armies were sent in to forcibly remove native Irish Chieftains from traditional homelands. The bloodbath that ensued was not going to prove fertile territory for the introduction of an English led religion.

For further reading: Gaelic and Gaelicized Ireland in the Middle Ages: K.W. Nichols. In Search of Ireland's Heroes: Carmel McCaffrey. Saints, Sacrilege and Sedition: Religion and Conflict in the Tudor Reformations: Eamon Duffy.

While Scotland geographically appears more like the Scandinavian countries, the reasons for its conversion to Protestantism have more to do with its relationship with England and France. The elite in Scotland became more resentful of the established church and its wealth in the 1530s. The church had an income ten times that of the crown, and its wealth came under assault in the first half of the sixteenth century. Authors like George Buchanan and John Bellenden produced works that sharpened the distaste towards the clergy among the Court of James V, and for Bellenden, created a more nationalist Scottish history in the vernacular. English evangelicals helped distribute bibles and protestant propaganda beginning in the 1540s. In the lead up to the break with Rome in 1560, the old church had lost respect as a landowner, was under assault by the new humanist biblical scholars, had been replaced as a center of learning by lay schools and hospitals, and was no longer the sole source of doctrine, as England and the Continents shipped and published Bibles in the vernacular, which Scottish nobles and the literate middling sort (lawyers and merchants) gobbled up.

By 1558, Queen Mary (of Scotland) had married the Dauphin of France, and had transferred royal control of Scotland to him. This forced the hands of the reformers in Scotland, and allowed them to link their cause for Reformation with the independence of Scotland from France. The monarch was in France, and French troops were the protectors of the old religion, which further inflamed the reformed Scots against them. The reformers saw an ally in England after the death of Mary I (of England) in November of 1558 and the ascension of Elizabeth. Between 1557 and 1560 more and more elites and landowners had come over to the evangelical cause. Knox had been made minister of Edinburgh in 1559, and most towns set up kirk sessions with reformed ministers. Scottish nobles refused to accept a foreign ruler, and instead joined with the reformers who had despised Mary for her Catholicism. The Reformation Parliament of 1560 in Scotland was made of up convinced Calvinists who broke the link with Rome and abolished the mass. The new Scottish Confession attempted to create a universal religious message for all believers, reduced the number of sacraments to just baptism and communion, and set the ground for the ideas of predestination.Although the majority of the population remained Catholic in 1560, the traditional religion had been effectively outlawed. The elite in Scotland and urban residents had lived without a strong monarch since the death of James V, and with the steady stream of protestant literature, came to be converted to the evangelical faith. Once there was the potential for an ally at home (Elizabeth of England), and the threat of foreign conquest from France, reformed belief joined cause with nascent Scottish nationalism, that allowed the Parliament of 1560 to lay the legislative groundwork to establish the Presbyterian system of the Scottish Kirk.

In Ireland, the Reformation never made much headway. Whereas in Scotland there was a growing number of elites who embraced the new religion starting in the 1530s, there was little incursion into Ireland. English dominance over Ireland was more de jure than de facto. Ireland's lower literacy rates also prevented any substantial increase in reformed ministers at home. The Reformation Parliament in Ireland in 1536 did pass legislation for Henry's Supremacy, but they were more concerned with the fallout from the Kildare Rebellion earlier in the year.

The Reformation also faltered because the rulers were more concerned with keeping peace among the warring lords than enforcing the religious settlement. Politics and power were the stakes for the universally Catholic landowners and family leaders in Ireland, and their near constant feuding in the 1530s prevented any religious headway. It was only in the 1540s that Henry tried to introduce the English Common Law over all of Ireland, with limited effectiveness. As time passed, more of Ireland came under English dominion, but even during the reign of Elizabeth, less than a third of the island was ever managed by English law or religion.

After Edward's brief reign, Mary restored Catholicism in England and Ireland. It was only under Elizabeth and the plantations that there was a concerted attempt to convert the island. By this time, the religion of Elizabeth looked like a foreign religion to the Irish, and it was being imposed by force. Irish resistance against English dominion went part and parcel with resistance against the new religion. The parts of Ireland that became Protestant were only converted due to the removal of native Irish and the in migration of English and Scottish.

Edit: Sources: Donaldson, Scottish Reformation; Wormald, Court, Kirk, and Community; Ryrie, Origins of the Scottish Reformation; Heal, Reformation in Britain and Ireland; Brady, The Chief Governors; Ellis, Ireland in the Age of the Tudors; Brigden, New Worlds, Lost Worlds.