Full Idea
We never can be absolutely certain that any given deliverance [of revelation] really is inspired; for that can only be established by reasoning.
Gist of Idea
Only reason can establish whether some deliverance of revelation really is inspired
Source
Charles Sanders Peirce (Scientific Attitude and Fallibilism [1899], II)
Book Reference
Peirce,Charles Sanders: 'Philosophical Writings of Peirce', ed/tr. Buchler,Justus [Dover 1940], p.57