Brenner, Lenni. Jefferson & Madison on Separation of Church and State: Writings on Religion and Secularism (Fort Lee, NJ: Barricade Books, 2004)
Reading 400 pages of any of the Founders' writings is the equivalent of several times the page count of nearly any contemporary writer, as this excellent collection of Jefferson's and Madison's writings proves. Although I have recently been spending more time on other things, I can't recall the last time it took three weeks to finish a single book. As always with the Founders, it was time well spent.
Brenner wisely chooses to present the writings--mostly letters--in chronological order, rather than trying to organize them thematically. Although the supplementary notes are generally good, they could have easily been more detailed; this could have been done without increasing the page count (or reducing the type size any further) by omitting The Jefferson Bible. Its inclusion was unnecessary, as it is readily available elsewhere (I recommend this edition from Beacon Press).
I don't mean to slight Madison, for his role in history is of the utmost importance, but most of the passages I noted while reading this book were Jefferson's. His words shine like beacons of reason across the centuries, and these two are no less appropriate in today's waning GOP era than during the end of the Federalist era in Jefferson's day:
"A little patience, and we shall see the reign of witches pass over, their spells dissolved, and the people recovering their true sight, restoring their government to its true principles." (p. 146, letter to John Taylor, 4 June 1798)
"...our fellow citizens have been led hood-winked from their principles, by a most extraordinary combination of circumstances. But the band is removed, and they now see for themselves." (p. 159, letter to John Dickinson, 6 March 1801)
Both Madison and Jefferson were highly critical of religious establishments and equally supportive of religious freedom, as even a casual student of history will already know. Madison referred to religious establishments as representing a "dishonorable principle and dangerous tendency," (p. 65, letter to Thomas Jefferson, 9 January 1785) and Jefferson derisively referred to the "loathsome combination of church and state" (p. 234, letter to Charles Clay, 29 January 1815).
Jefferson's antipathy toward the priesthood's Pauline and Platonic corruptions of what he called "primitive Christianity" may take some readers by surprise, as he repeatedly compared them to a "dunghill" surrounding the "diamonds" of Jesus' words (e.g., p. 211, letter to John Adams, 12 October 1813; p. 216, letter to John Adams, 24 January 1814; p. 247, letter to Francis Van der Kemp, 25 April 1816). Jefferson was perhaps most forthright with Adams, writing the following to his upon the disestablishment of the Congregational Church in Connecticut:
"I join you therefore in sincere congratulations that this den of the priesthood is at length broken up, and that a protestant popedom is no longer to disgrace the American history and character." (p. 259, letter to John Adams, 5 May 1817)
Concerned in his later years with not offending others with his unorthodox opinions, Jefferson wrote: "I take no part in controversies, religious or political. At the age of 80, tranquility is the greatest good of life, and the strongest of our desires that of dying in the good will of all mankind." (p. 367, letter to James Smith, 8 December 1822) My Quote of the Day is from Jefferson's final letter, wherein he declined to appear at a July 4th event which was to be his last day alive:
"May it [half a century of experience and prosperity] be to the world, what I believe it will be, (to some parts sooner, to others later, but finally to all,) the signal of arousing men to burst the chains under which monkish ignorance and superstition had persuaded them to bind themselves, and to assume the blessings and security of self-government. [...] All eyes are opened, of opening, to the rights of man. The general spread of the light of science has already laid open to every view the palpable truth, that the mass of mankind has not been born with saddles on their backs, not a favored few booted and spurred, ready to ride them legitimately, by the grace of God." (p. 390, letter to Roger Weightman, 24 June 1826)
I can't praise Jefferson and Madison highly enough, and Brenner has done very useful work in publishing this useful compendium of their words of wisdom on religion and secularism. As Brenner notes in the Scholar's Afterword:
The [political] hacks claim to represent patriotism. Every year July 4th rolls around and they pay lip service to Jefferson's ideals. They can still get away with it because the broad public has no awareness of what he and Madison really stood for. So, let us take Jefferson's Bible and Madison's Memoranda to the people. (p. 406)
The Thomas Jefferson Collection at the Library of Congress
The Thomas Jefferson Digital Archive at the University of Virginia
The Constitution Society has a text-only version of all 19 volumes of The Writings of Thomas Jefferson
The Avalon Project at Yale Law School has collections of papers from Jefferson, Madison, and some--but not all--other presidents.