/You just do not understand how dangerous it would be for us to have a Muslim President./
As long as he/she doesn't let his/her beliefs get in the way of leading the country, there would be no problem. The same would apply to a person of any other religion, including Christianity.
/You think we Christians are bad/
Since I am a Christian, no, I do not believe all Christians are bad. I think narrow-minded, bigoted, fundamentalist Christians who give Jesus a bad name are.
/but we let you to have a free will./
I thought that was God. Are you comparing yourselves to Him? What blasphemy! By the way, you and your ilk don't "let" people do anything. People are individuals, and as such, make their own choices and have their own free will without interference from others.
/It is far worse in my book to be a Muslim than a black./
Congratulations, you are not only a religious bigot, you are a racist. How lovely.
/There is only one race, human race./
Which Muslims and blacks are part of, you ridiculous dimwit! My Lord.