Having written the Constitution, the Framers remaining at the Constitutional Convention in 1787 (roughly 40 out of around 80 original attendees) had to find a way to get it enacted. They decreed (quite illegally) that special conventions would be called in each state, and that once 9 of the 13 states had approved, the Constitution would replace the Articles of Confederation as the governing document of the land. Small states quickly ratified the Constitution, realizing that the existence of the Senate would give them more power than they could hope for under any other form of representative government. But, no matter how many small states adopted the Constitution, it was understood that without the big four, Pennsylvania, Massachusetts, Virginia, and New York, either the Articles would stay in place or the nation would divide.
The Pennsylvania political machine quickly rushed through ratification before opponents of the Constitution, called "anit-federalists" could get organized.
Massachusetts was under the rule of a political machine headed by Paul Revere, Samuel Adams, and John Hancock. Supporters of the Constitution, called "Federalists", and was brought around when the Federalists hinted to Hancock that there would be a new office called "President", and, well, it was his name that was so large on the Declaration...
New York was the last to accept, and was the location of a series of famous debates, which included the publications that have been collected as the "Federalist Papers".
Virginia, however, is the state which concerns us. It ws the location of the first major (rhetorical) battle between the Federalists and the anti-federalists. By May of 1788, 7 states had voted for the Constitution, and 1 against (Rhode Island), and Virginia was beginning its own process of debate.
Supporting the anti-Federalists were George Mason, the influential Lee family, Edmund Randolph, and, most importantly, Patrick Henry. The Federalist proponents were John Marshall, James Madison, and, above all, George Washington (Thomas Jefferson was currently serving as ambassador to France, though he was in spirit on the side of the anti-Federalists).
The primary concerns of the anti-federalists in Virginia were twofold:
1) there is no Bill of Rights to defend the states and the people from the potential power of the new federal government;
2) there is no mention of God in the Constitution.
Rather than let the state be swept up in a bitter debate, George Washington personally intervened, promising on his own reputation that a Bill of Rights would be added to the Constitution which would include a defense of religion and liberty. Based on this, Edmund Randolph switched sides and Virginia ratified the Constitution, including proposing twelve amendments for the consideration of Congress (once it had been formed).
In a rare occurance in American politics, the Federalists kept their word and supported ten of the twelve proposed Amendments, creating our current Bill of Rights, including the First Amendment.