Sacredfire
George Washington’s Sacred Fire aims to set the record straight about Washington’s faith, with 15 years of historical research and a clear explanation of what deism is and why Washington does not fit that description.  Should be an interesting read.

Most other books published about George Washington’s faith argue for Washington’s religious convictions based on anecdotal evidence that often either cannot be substantiated, or possess questionable authenticity. George Washington’s Sacred Fire will leave you awestruck by the faith, values and ideals of this great founder of our nation — the reader will see him as a unique role model for generations of Americans.

In this same vein, you might want to check out Novak’s Washington’s God, written at the request of Mount Vernon, and using their archives.