An Answer to a Book Intituled, Christianity as Old as the Creation. In Two Parts. Part I. In which that Author's Account of the Law of Nature is consider'd, and his Scheme is shewn to be inconsistent with Reason and with itself, and of ill Consequence to the Interests of Virtue and the Good of Mankind. Part II. In which the Authority and Usefulness of the Revelation contain'd in the sacred Writings of the Old and New Testament, is asserted and vindicated, against the Objections and Misrepresentations of that Author. By John Leland, D.D.