Jefferson said specifically about Christianity:Jefferson DID NOT SAY America was not founded as a Christian Nation. AND when he says we Obama needs to have a mouse in his pocket or say I. When it comes to religious beliefs he may only speak for himself. BUT you are correct about context, and the left love to take things out of context just as much as the right. Sadly Americans have to choose between left and right, and neither one is worth the manure it would take to cover them up.
Where the preamble declares, that coercion is a departure from the plan of the holy author of our religion, an amendment was proposed by inserting "Jesus Christ," so that it would read "A departure from the plan of Jesus Christ, the holy author of our religion;" the insertion was rejected by the great majority, in proof that they meant to comprehend, within the mantle of its protection, the Jew and the Gentile, the Christian and Mohammedan, the Hindoo and Infidel of every denomination.
-Thomas Jefferson, Autobiography, in reference to the Virginia Act for Religious Freedom
Look it up.