IT’S notable how we take islands for granted in Scotland. Plenty other places don’t have them. They are of us and off us. They configure themselves in the psyche by virtue of visible jigsaw coastline.

In centuries past, some were sought by holy men for contemplation until invaded by mighty Viking warriors battling bravely against unarmed, pacifist monks.

Iona is said to be the birthplace of Christianity in Scotland, and so has much to answer for. Lying a mile from Mull in the Inner Hebrides, it’s small, about three miles long by one and a half wide. Visitors can’t bring cars but, sadly, bicycle hire is available at the pier.

The residents must spend a lot of the time running about and hiding, as they seem difficult to count. I’ve seen current population estimates of 120, 125, 130 and 170. They live mainly off crofting, craftwork and tourism. There’s said to be a “special atmosphere”, borne of tranquillity, which would be unusual in any place where Earthlings – defined in my Guide to the Universe as “essentially noisy” – are found.

The foundation for Iona’s fame lies in its abbey and, for its origins, we must spin dizzily back in time to 563 AD, when a holy man called Columba arrived from Ireland with 12 companions. In those days, Iona lay within the Gaelic kingdom of Dál Riata, which you thought was a side-dish for curry.

Unreliably born in 521 AD, Columba, or Colm Cille, was reportedly a prince, who in his youth became a turbulent priest known for his hot temper. The disputed story (concocted long after his time) goes that, as a skilled scribe, he got into a ruck about a book. Unlike today, books back then were revered and ownership of them prized.

Ordered to hand over a copy of the Psalter of St Jerome he’d illicitly made, Columba (allegedly) raised an army and in 561 AD fought a battle – the, er, Battle of the Book – in which 10,000 people died. Religion, eh? Remorseful about the carnage, he and his 12 followers (must have been big lads to kill so many thousands) fled into exile.

After mucking about for a bit, they finally settled on Iona and, as was their wont, built a church-cum-monastery from clay and wood. Columba supposedly had great physical and mental strength and, while he was much loved by his followers, they also feared a rollicking.

That daft wee monastery became highly influential as a centre for Celtic Christianity, playing a role in the conversion of the Picts in the late 6th century and the Anglo-Saxons of Northumbria in 635. Columba, be it noted, died on Iona on 9 June 597, but his work lived on.

The first Celtic crosses – ken, the ones with a ring or nimbus on them – were thought to have been erected on the island, which became a renowned centre of learning, with a scriptorium producing important chronicles. Unfortunately, the monks got kicked in the chronicles when the vaguely Satanic Vikings arrived for the first of many holidays in 794.

Columba's relics were removed in 849 and divided between Dunkeld in Perthshire and Kells in Ireland, as the monastery struggled to survive and gradually fell out of influence. However, in the 12th century, after the Norse had been kicked out of the Hebrides, Somerled, first Lord of the Isles, reportedly had St Oran’s Chapel built as a family burial place on the island and, later, his son Ranald founded a Benedictine abbey on the site of Columba’s old monastery.

An Augustinian nunnery was also established, with Ranald’s sister Beathag or Bethóc (in English we say Beatrice) bunged in as first prioress. The abbey remained a famous place of worship and pilgrimage until the Reformation of 1560 when it, and the nunnery, were destroyed in a fit of religious enthusiasm.

However, the abbey remains the best-preserved ecclesiastical building from the Middle Ages in the Hebrides, and ruins of the nunnery are still visible. The gardens there are said to be particularly pleasant. Nothing remains of Columba’s original settlement except an earthen bank that enclosed it.

Of the many Celtic crosses, only four survive, one in situ and three in the Abbey museum. To the left of the Abbey entrance, a small roofed entrance, believed to be a 9th or 10th century shrine, can be seen.

Rèilig Odhrain, the ancient burial ground, contains the 12th-century chapel of St Odhrán reputedly also the graves of many early Scottish monarchs, as well as Norse kings from Ireland and Norway. Notable burials there include (feel free to read these out as football results for your coupon): Kenneth I or 1, Donald II (2); Malcolm 1, Duncan 1; Donald 3, Macbeth 0. John Smith, the Labour Party leader who loved Iona, is also buried there.

The island is now owned by the National Trust for Scotland, which received it in 1980 from the Fraser Foundation, which in turn had purchased it from the Duke of Argyll in 1979. The abbey is owned by the Iona Cathedral Trust, and its buildings cared for by Historic Environment Scotland, which fleeces people for £9.50 a skull (with some concessions) to go in. Around 130,000 do so every year.

Iona still plays an active role in the promulgation and development of Christianity. Famous English visitor Samuel Johnson, whose verbosity is here edited, said of the place: “That man is little to be envied whose … piety would not grow warmer amid the ruins of Iona."

In 1938, George MacLeod, a minister of the Church of Scotland in Govan, who wanted to bridge a perceived gap between organised religion and ordinary folks, heated things up by founding the ecumenical Iona Community, which today runs two residential centres on Iona and one on Mull.

Ruth Harvey, current leader of the community, says: "People come for reflection and inspiration, and to explore issues of importance – the environment, poverty, migration, equality – in the context of a Christian community and in a beautiful, rugged landscape.”