Britain became the first "foreign" field for the many Irish Celtic missionaries, who burned with love for Christ, fearing no peril or hardship and went everywhere with the Gospel. The church in Britian would later become enmeshed in the Roman Catholic system, but it was the land of Britain that would centuries later provide the empetus for global evangelism of the 19th century.

The Celtic missionaries conducted a purer (than the Roman Catholics) form of missionary work. They would visit a country & found a missionary village, a church in the center and school-rooms and huts for the monks around it who were preachers and teachers. Outisde this were dwellings for students and their families and a wall enclosed all of it. Groups of 12 monks would go out and share the Gospel and the rest would stay to teach and learn the language of the people in order to translate the scripture for the people. The missionaries were free to marry or remain single. Gradually, they trained the local people to carry on the work of the Gospel and train them in handicrafts and languages and how to explain the Gospel to others. They delayed baptism until the convert was well grounded in the faith. This was all independent of Rome and the Roman Catholic church.

Columba was one of the most famous of these Celtic abbot-missionaries. He was born into an Irish family in 521 & brought up in the Christian faith. He entered a monastery & was ordained a deacon, then a priest. He established many churches & monasteries in Ireland.

He switched to "foreign" missions at age 42 because of his apparent hot temper and quarrels and got into war with King Diarmuid. A battle was fought in which 5000 men were killed. Columba fled from Ireland in 563 and resolved to convert as many souls as had fallen.

He established his headquarters just off the coast of Scotland on Iona and established a monastery, which provided training for evangelists. Columba is credited with having evangelized the Picts who livled in the Scottish highlands. Through his witness, King Brude, who reigned over the northern Picts, was converted.

Although Columba's missionary efforts were important, there were many other missionaries from Ireland and elsewhere doing evangelism in this area who were not associated with him. There was strong competition between Roman Catholic and Celtic missionaries and the Catholics eventually gained the upper hand. The initial work of evangelizing much of Britain & central Europe was accomplished by the energetic & faithful Celtic monks.