Robert Austin Markus, OBE, FBA (8 October 1924 – 8 December 2010), born Róbert Imre Márkus, was a Hungarian-born British historian and philosopher best known for his research on the early history of Christianity.

[3] The factory was soon producing precision machine tools for the manufacture of Spitfires, which enabled the family to avoid internment as enemy aliens on the Isle of Man.

[1] Márkus had originally sought to study philosophy, while his father wanted him to become and engineer and assume control of the family business, and chemistry thus became a compromise choice.

[1] At Manchester, Márkus belonged to a circle of future prominent intellectuals, which included Walter Johannes Stein, Herbert McCabe and Eric John.

[1] Several members of the group were Marxists, most notably his close friend Walter Stein, and throughout his life, Márkus would belong to the political left.

[4] Among the members of Markus' intellectual circle was the history student Margaret Catherine Bullen, with whom Marcus would eventually marry.

Seeing the need for Christian conscience in the aftermath of the invention of nuclear weapons, Márkus received instruction as a Catholic from Father Whelan in 1946.

[1] Together with Walter Stein, Willy Schenk and Louis Allen, Robert founded the journal Humanitas, which aimed to united Catholic values and social reform through radical change of both the Church and secular society.

At the time Markus lectured on a number of subjects, including Bede, and on ancient and medieval political thought.

[7] Along with Brown, Markus played a decisive role in establishing Late Antiquity as a distinct period in European history.

[1] Markus argued that the growth of Christianity was largely achieved through its gradual incorporation of classical values, which made it more acceptable to Roman elites.

His The End of Ancient Christianity (1990) examined how Roman culture eroded from the time of Augustine to that of Pope Gregory the Great.

[12] A festschrift, The Limits of Ancient Christianity: Essays on Late Antique Thought and Culture, was published in honor of Markus in 1999.

A Roman Catholic, Margaret was the daughter of John Joseph Bullen, who managed a shop for the Co-operative Wholesale Society in the Wirral.