Due to his engagement in the arts and service as chair of the Council for Museums and Galleries in Scotland, Walls received an Order of the British Empire in 1987.

[7] With his late wife Doreen Harden (1919–2009), whom he married in 1953, they have two children, Christine and Andrew (an immunopharmacologist at the University of Southampton).

[12] After his death, scholars and former students from Africa, Asia, Europe, and the Americas paid tribute to Walls's ground-breaking scholarship and generous personal support.

[14] His pioneering research led the magazine Christianity Today to describe him in 2007 as 'a historian ahead of his time' and 'the most important person you don't know'.

[15] Although he is more well known for his work in Christianity, Walls has also been a significant pioneer in shaping the field of religious studies as it is taught in universities of Scotland.

It would also be in this new department that the original Centre for the Study of Christianity in the Non-Western World was established, before eventually being relocated to the University of Edinburgh in 1987.