Follow up with American Religious History professor

I wanted to follow up (see previous blog) with the conversation I had with my professor of "American Religious History" who has hardly included Judaism and has completely excluded Islam from our class that has a focus on education to foster ecumenical dialogue and understanding. I write this out of a sincere desire to know if what he said was true, as it completely baffles me.
At first he responded to my question around the short time we spent on Judaism by saying that Judaism really isn't big in the picture of U.S. religious history. That we are an overwhelmingly protestant country, religiously and culturally, and Judaism just isn't a big part in our history. Ok, I can kind-of understand that. But I grew up protestant! Of course I can understand a history that mirrors my own personal identity. Is Judaism's small impact on U.S. religious history really true?
When I asked about Islam, the professor defended himself by saying that this isn't a world religion's class and then what about Buddhism and Hinduism and Indigenous religions? I agreed that you have to make choices in creating a class and that there is power in limiting one's scope so one can go deeper. However, Islam, Christianity and Judaism are particularly relevant to one another as Abrahamic religions, religions "of the book." I explained where my question was coming from- from learning about Andalusia (which was very significant in the time and region when explorers were making their way to the "New World.") Islam and Christianity and Judaism were very much in relation with one another, so isn't it possible Islam affected the Catholicism and even the Protestantism that came over to the Colonies? His answer: no. As simple as that- Islam did not affect Catholicism or Protestantism when they founded and spread in the "New World."
Somehow I can't quite believe this. I think of how African American slaves found each other and were able to understand one another because of the exact tune and rhythm of the Islamic prayers they grew up. And how African Americans formed whole denominations and cultures within Protestantism. I also wonder how Islam influenced Catholicism and Protestantism before the start of slavery, and outside of the slave trade. Any thoughts?