Scotland's religious history parts from England's at the Reformation and never rejoins it. The Scottish Reformation of 1560 was carried by the nobility and the burghs against the crown rather than by it, and the Scots Confession drawn up that year was adopted by parliament. The church that resulted was Presbyterian: governed by courts of ministers and elders rising from the kirk session through presbytery and synod to the general assembly, without bishops above them. The Westminster Confession of 1646 became its doctrinal standard and remains the church's subordinate standard today.
The question of who governs the church then ran through Scottish public life for three centuries. Attempts by the Stuart kings to impose bishops and a prayer book produced the National Covenant of 1638 and a war fought partly over liturgy. The right of a landowner to present a minister to a parish against the congregation's wishes split the church repeatedly, most seriously in the Disruption of 1843, when more than a third of the ministers walked out of the general assembly to found the Free Church and gave up their stipends and houses to do it.
Before all of this the country had been Christianised largely from the west. Columba founded the monastery on Iona in 563, and the Irish monastic mission working from it carried Christianity through the north and into Northumbria. The Picts, whose carved stones survive in numbers across the northeast, are known almost entirely from those stones and from outside accounts.