John Adams on belief in God as a necessary predicate for belief in natural law

"To him to believes in the Existence and Attributes physical and moral of a God, there can be no obscurity or perplexity in defining the Law of Nature to be his wise benign and all power Will, discovered by Reason.  A Man who disbelieves the Being of a God, will have no perplexity in defining Morality or the Law of Nature, natural law, natural Right or any such Things to be mere Maxims of Convenience, to be Swifts pair of Breeches to be put on upon occasion for Decency or Conveniency and to be put off at pleasure for either."

-- Letter to Thomas Boylston Adams, March 19, 1794, quoted in The Founders on Religion:  A Book of Quotations, edited by James H. Hutson (Princeton:  2005), pg. 132.