There is clear evidence to show that a Christian community was established between the Don and the Dee by the end of the sixth century, possibly by St Machar, a disciple of St Columba.
By 1131, as a result in part of the Gregorian reforms and those of St Margaret and her royal sons, and in part by the development of an urban society based upon commerce and trade, the Episcopal centre for the north-east of Scotland, which was formerly at Mortlach, in Banffshire, had been transferred to St Machar’s in Old Aberdeen which then became the Cathedral of the Diocese.
In the course of the twelfth and thirteenth centuries the diocesan boundaries were defined and the administrative structures firmly developed in line with the rest of the Scottish Church and those of the Western Church itself. Thereafter, throughout the middle Ages, the bishops of Aberdeen played their full part in the religious, social, economic, cultural and educational development of their diocese and of the country itself. All were royal advisors, formulating and shaping the laws of the land. Two of them became Chancellors of Scotland. Others served as ambassadors, negotiating peace treaties and encouraging trade with foreign powers.
They beautified and enlarged their Cathedral, and established a grammar and song school for the training of the Priests and vicars choral. They founded three hospitals and almshouses for the poor in Old Aberdeen itself. They established excellent relations with the royal burgh of Aberdeen and built its first bridge over the river Dee. One of them introduced printing into the country, published the first Scottish breviary and in 1495, founded the University of Aberdeen. It is not surprising, therefore, that the diocese of Aberdeen played little part in the uprising which led to the Scottish Reformation, or in the Act of Parliament in 1560 which abolished papal authority and jurisdiction throughout Scotland.
During the following century many of Scotland’s Catholic minority lived north and west of Aberdeen. With Presbyterianism finally established after 130 years of religious conflict, fresh penal laws were enacted by the Edinburgh parliament. Jesuits educated in their colleges in Rome and elsewhere, had been the first priests to come to the houses of certain leading families, but thereafter a variety of regular and secular clergy were involved. In 1694 Scotland’s first Vicar Apostolic was appointed to bring episcopal order to the scattered missions. From a base at Preshome, near Buckie, on the Moray Firth, he made contact with the west coast and the Hebrides, supporting the efforts of missionaries from Ireland.
Even after a Highland District had been created, the Lowland District included Gaelic-speaking Catholic areas, of which the most significant was Glenlivet. There, the seminary of Scalan gave education to a hundred priests in the eighteenth century, as well as providing an annual meeting place for Scotland’s senior clergy.
1829 saw the creation of a Northern District (effectively the modern diocese of Aberdeen.) The National Seminary was transferred to Blairs outside Aberdeen. Irish immigration brought a great increase in Catholic numbers in south-west Scotland. They were attended by northern priests, and seven 19th century bishops came from the area around Preshome. The Northern District’s new challenge came from the establishment of new fishing communities along the Moray Coast, in Caithness and as far as Shetland.
For a while in the 1860’s, Caithness and the Northern Isles became part of a separated ‘Arctic Mission’. They were reincorporated into the Northern District prior to the re-establishment of the hierarchy in 1878, when the bishop at Preshome moved to Aberdeen.