Turns out the Founder Fathers you've heard of all read and studied it.
Thomas Jefferson, especially, had a familiarity with Islam that borders on the astonishing. Like Adams, he owned a Koran, a 1764 English edition that he bought while studying law as a young man in Williamsburg, Va. Only two years ago, that Koran became the center of a controversy, when the first Muslim ever elected to Congress, Keith Ellison, a Democrat from Minnesota, asked if he could place his hand on it while taking his oath of office — a request that elicited tremendous screeches from the talk radio extremists. Jefferson even tried to learn Arabic, and wrote his Bill for Establishing Religious Freedom to protect “the Jew and the Gentile, the Christian and the Mahometan, the Hindoo and infidel of every denomination.”
Once again, the principle of "freedom of religion" was originally intended to apply to Muslims as well.
This theory was eloquently expressed around the time the Constitution was written. One of its models was the 1780 Massachusetts Constitution, which John Adams had helped to create, and which, in the words of one of its drafters, Theophilus Parsons, was designed to ensure “the most ample of liberty of conscience” for “Deists, Mahometans, Jews and Christians.”
And even African slaves of the Muslim faith kept it alive.
While evidence is fragmentary, as many as 20 percent of African-American slaves may have come from Islamic backgrounds. They kept their knowledge of the Koran alive through memory, or chanted suras, or, in rare cases, smuggled copies of the book itself. In the 1930s, when WPA workers were interviewing elderly African-Americans in Georgia’s Sea Islands, they were told of an ancestor named Bilali who spoke Arabic and owned a copy of the Koran — a remarkable fact when we remember that it was a crime for slaves to read. In the War of 1812, Bilali and his fellow Muslims helped to defend America from a British attack, inverting nearly all of our stereotypes in the process.
Given the anti-Christian/Jewish sentiment popular in the various fundamentalist strands of Islam today, the following is an interesting historical contrast:
Jefferson and Adams led many of our early negotiations with the Islamic powers as the United States lurched into existence. A favorable treaty was signed with Morocco, simply because the Moroccans considered the Americans ahl-al-kitab, or “people of the book,” similar to Muslims, who likewise eschewed the idolatry of Europe’s ornate state religions.
So, to sum up, America's Koran-versed Founding Fathers explicitly included Islam into American society, and at least one Muslim nation saw Americans as "people of the book."
...now if only we can get millions of people across the world to realize this. Otherwise, forgotten history will triumph once again in favor of self-serving story lines.