The papers and correspondence reflect Forbes's preoccupation with the Scottish Episcopal Church, its doctrines and particuarly its liturgy, to the study of which he devoted himself. It also reflects the various controversies in which he became involved, notably a serious disagreement with his Bishop, Charles Wordsworth over the Prayer Book, which ended in litigation.
The collection also contains material relating to Forbes' own works of scholarship, his research on St Gregory of Nyssa, on Ecclesiastes and Job and to the more populist aspect of his writings, reflected in the two magazines, the Gospel Messenger and the Panoply. These were begun and largely written by Forbes himself and were printed and published at the Pitsligo Press, Burntisland. There are also printed items within the collection as well as material from the decade after Forbes' death, particularly relating to the division between the Scottish Episcopal Church and the English Episcopal Church in Scotland and the attempt to heal the breach.