They were published as follows: Natural Religion Insufficient, and Revealed Religion Necessary, to Man's Happiness in his Present State (1714), an able statement of the orthodox Calvinistic criticism of the deism of Lord Herbert of Cherbury and Charles Blount; Memoirs of the Life of Mr Thomas Halyburton (1715), three parts by his own hand, the fourth from his diary by another hand; The Great Concern of Salvation (1721), with a word of commendation by I.
His principal works are Remarks on the Internal Evidence for the Truth of Revealed Religion (1820), an Essay on Faith (1822), and the Unconditional Freeness of the Gospel (1828).
Unfortunately, failing health compelled him to abandon the second or constructive part: the first, a brilliant piece of writing which attempts to show the ethical inadequacy of revealed religion and is marked in parts by much bitterness, was published in 1887 under the title of The Service of Man.
A revealed religion could never obtain universality, as it could never be intelligible and credible to all men.
His chief theological and philosophical works were Institutes of Natural and Revealed Religion (3 vols., 1772-1774); History of the Corruption of Christianity (2 vols., 1782); General History of the Christian Church to the Fall of the Western Empire, vols.
He seeks to show not onl y that the difficulties in the systems of natural and revealed religion have counterparts in nature, but also that the facts of nature, far from being adverse to the principles of religion, are a distinct ground for inferring their probable truth.
It simply means that a certain religious and philosophical tendency, which grew up slowly on Greek soil, was already implanted in those who occupied the vantage-ground of a revealed religion of redemption.
In theology he was not a naturalist or a deist, but a believer in the necessity of revealed religion for salvation.