Whilst religious affiliation within Aberdeen is diverse, the majority of the population (58%) declared no religion in the 2021 United Kingdom census.
In the Middle Ages, Aberdeen contained houses of the Carmelites (Whitefriars) and Franciscans (Greyfriars), the latter surviving in modified form as the chapel of Marischal College as late as the early 20th century.
The large kirkyard of the Kirk of St Nicholas is separated from Union Street by a 147 ft (45 m) long Ionic façade, built in 1831.
The divided church within, with a central tower and spire, forms one continuous building 220 ft (67 m) in length.
The pre-Reformation Diocese of Aberdeen is said to have been first founded at Mortlach in Banffshire by Máel Coluim II (1005–1034) to celebrate his victory there over the Danes, but in 1137 David I (1124–1153) transferred the bishopric to Old Aberdeen, and twenty years later St Machar's Cathedral was begun, a few hundred yards from the river Don.
The last remaining church congregation in Belmont Street has now moved to Union Square South Christ Central.