On a wide range of policy issues, the Republican party is closer than the Democratic party to the opinions of the average American Muslim as expressed in opinion polls. American Muslims are a pretty conservative group on many social and economic issues. But, those Muslims are still going to vote for Democrats (and more than 80% of the American Muslim adults are U.S. citizens).
Because a lot of Republicans are very stridently anti-Muslim.
For example, two-thirds of likely Republican voters favor prohibiting Muslims from entering the United States, and a third of likely Republican voters in North Carolina believe that Islam should be illegal in the United States and favor closing mosques in the United States.
Basically, a large swath of Republicans hate America and everything it stands for, which is really quite unfortunate for the future of our country.