Remarks on a Piece Wrote by Mr. Isaac Backus, of Middleborough, Printed in 1768 (called, "An Examination of Nine Sermons from Matth. 16. 18. Published Last Year, by Mr. Joseph Fish, of Stonington") : Wherein Those Sermons are Vindicated, from the Exceptions Taken Against Them by Mr. Backus--many of His Errors Confuted, and His Mistakes Corrected