Natural faith, as we have already had occasion to see, is faith arising naturally on its appropriate natural occasions, directed to its appropriate natural objects, and sustained by the operation of natural causes. Religious faith, if we have a right understanding of it, may be regarded as in some respects a state of mind the same with that of natural faith; that is to say, it may be regarded as the same state, psychologically or mentally considered; but it differs from natural faith in the particulars, that it is directed to religious objects, or those objects to which religious feelings are appropriate; that it is called into exercise on its appropriate religious occasions; and is sustained by religious influences. It is obvious, therefore, that the difference between natural faith and religious faith is a marked and a great one; and that it would tend to great perplexity and error, if they should be confounded together. At the same time it is evident, I think, that in a number of particulars there is a resemblance or analogy existing between them, which it is not only interesting to contemplate, but which may aid in the better understanding of religious faith.
— edited from The Life of Faith (1852) Part 1, Chapter 3 by Thomas Cogswell Upham. His blog is managed by Craig L Adams and can be found here: http://thomascupham.blogspot.com