The name of Andrew Alexander Bonar probably first brings to mind the book: Memoir or M'Cheyne. Many people remember him also as the beloved pastor and preacher of the Collace Church, and later of the Finnieston Church in Glasgow. It is often overlooked that he was regarded by his contemporaries as a respected writer on various subjects, and as a great moral influence in the Church. This thesis represents an attempt to investigate the life, work, and religious thought of Bonar, and to present the results of that investigation objectively, critically, and constructively.