Collins’s first major work, which like all his others, was published anonymously. In the Essay Collins demanded that all revelation should conform to man’s natural ideas of God.

In the Letter Collins argued that it is possible that the soul may be material and, secondly, that if the soul is immaterial it does not follow, as Samuel Clarke had contended, that it is immortal.

Probably Collins best-known work in which he defends freedom of expression; it caused a sensation and was bitterly attacked by most of the leading writers of the time, including Swift, Addison, Berkeley, Bentley, Hoadly and Steele. His position is generally thought to be deistic; however there is evidence to suggest that he was an atheist. According to Berkeley, Collins claimed to have a proof for the non-existence of God; and many of his published statements seem to hint at, or imply, atheism. T. H. Huxley described him as the ‘Goliath of Freethought’.

There were at least five contemporary editions, all of which appear to be the first edition. However, the true first editions contains the famous, and probably deliberate mistranslation “idiot evangelists” (for “idiotis evangelistis” on p.90) and the Errata, most of which were also probably deliberate, enabling Collins to say something subversive while appearing to retract it, as for example with the fourth erratum “If a Man be under an Obligation to list to any Revelation at all” - which is really the main question of Collins’ Discourse. The Discourse was translated into French in 1714 and went into a second French edition three years later.

Writing as a Christian in defence necessitarianism, Collins aimed to demonstrate how it was from their lack of liberty that revealed men to be perfect, creatures: liberty is “both the real foundation of popular atheism and...the professed principle of the atheists themselves”. Collins unites Hobbes metaphysical determinism and Locke’s psychic determinism. The work was translated into French in 1754 and referred to by Melchior Grimm in his Correspondance littéraire in December of the same year. Attacked by Samuel Clarke, Collins published a reply, Liberty and Necessity, after Clarke’s death in 1729.

Published with a Preface entitled An Apology for Free Debate and Liberty of Writing. The Discourse was written ostensibly in opposition to William Whiston’s attempt to show that the books of the Old Testament originally contained prophecies of events in the New Testament which had been corrupted by the Jews and that the fulfillment of prophecy by the events of Christ’s life was “secondary, secret, allegorical and mystical”. Collins’s work provoked at least 35 rejoinders, including those by Samuel Clarke, Arthur Sykes and Biship Edward Chandler. Collins replied with Scheme of Literal Prophecy Considered in 1727. Holbach translated and published a French edition in 1768.