Jefferson wrote that because those on the "Christian Right" in his day did not understand that. And even today they still don’t, because they believe in false interpretations of symbolic scriptures and especially in erroneous and inaccurate notions that can be found in the New Testament.
That is one of the main reasons George W. Bush waged war in Iraq, because his "Christian" advisors led him to believe his war in Iraq is "God's Will" and fulfills the prophecy of the warring "sixth angel, who "poured out his vial upon the great river Euphrates..." (Revelation 16:12) They don't realize that chapter is mostly symbolic, just as so many things are in the New Testament. As Adamson explains, Jesus and John did foresee the wars we have been having, but that does NOT mean wars need to continue to fulfill prophecy.
Most of the above was quoted or paraphrased from the prophesied message from the Spirit of truth, which is summarized at:
http://reformationcomingsoon.bravehost.com
(Note: You can view every article as one long page if you sign up as an Advocate Member, or higher).