[1500s-1600s] Scottish Protestant Reformation
[300s-1100s] Celtic Christianity
Celtic Christianity describes an early form of Christianity, separate and distinct from Roman Catholicism, that took root in Ireland and Dal Riata (Northern Ireland and Eastern Scotland). It attributes itself as founded by missionaries from the Early Christian Church (35CE-400CE) to the British Isles. The Celtic or Gaelic Church is known as the church who spread Christianity to the British Isles, establishing hundreds of churches and several communities that became major European centers for learning in Christianity, Latin, education, and other sciences during the Dark Ages.
The early Celtic connection with the first-century Christian Church is clearly seen, but not always recognized, in the New Testament book of the Apostle Paul to the Galatians, who were Celts living in the area of modern-day Turkey. Over the centuries, the Celts who had once dominated most of Europe and even sacked Rome in their history, it is known their migration retreated to the edges of Europe in the British Isles, France, Portugal, and Spain (where there is a region called Galicia still today). Preceding Saint Patrick in 431, Palladius is considered the first Roman Catholic missionary to Ireland in an unsuccessful effort to convert exiting Christians to Roman Catholicism. While the legend of Saint Patrick states he brought Christianity to Ireland, and while he IS known for its spread, historical records reveal that Christianity was spread there much earlier and that "faith" that took hold of Ireland and the Celtic Church was not Roman Catholic but much closer to the Early Christian Church and the Apostles.
♦ Wikipedia articles: Celtic Christianity, Saint Columba (521-597), Apostle to Scotland; Aidran (-651), Missionary to Northumbria (Northeast England); Synod of Whitby (664); Saint Dunood, Missionary to Wales; Columbanus (540-615), Missionary to France, Germany, and Italy; Saint Cuthbert (634–687), Bishop of Lindisfarne; The Lindisfarne Gospels (720), was a Latin edition of the Gospels with the first (old) English version of the Gospels (wikipedia, british library); Book of Kells (800), Latin translation of the Gospels (wikipedia, digital online).
future additions -- Modern era, Catholic era, and pagan era