It seems like an important question to ask, especially in light of the heightened Islamophobia in the West thanks to ISIS's actions. Many political pundits and bloggers appear to have been using the Founding Fathers own words and/or letters in their justification for why America should be against Islam.
A recent example is Fox Business Network reporter Elizabeth McDonald stating: "the founding fathers—John Quincy Adams and his father John Adams—said virtually the same thing. They warned about the dangers of Islamists basically acting with natural hatred toward infidels, who in Christianity preaches the direct opposite.”
And many American conservative posts in the last few years have stated the same thing: The Founding Fathers were against the religion of Islam. Of course, arguments have been made for the opposite side; including the famous book "Thomas Jefferson's Quran: Islam and the Founders" and an article written by James Hutson for the Library of Congress
But did the Founding Fathers really had an opinion of Islam? And if so, what were those opinions?
My understanding is that Thomas Jefferson in particular was strongly for the toleration of Muslims. He wrote a great deal on the importance of religious freedom and tolerance for other cultures and ethnicities.
In contrast, other founders like John Jay and Alexander Hamilton wrote about the importance of Christians being in control of the United States, and how supposed infidels should not be tolerated. In the election of 1800 there were even a few rumors flying around that Jefferson was a Muslim, due to his publicly professed views on the toleration of Muslims.