"But several Rabbis I talked to recently still gave over the opinion that Islam was a monotheistic religion and it is ok to go to mosque but not to church. "
Technically yes, (thats what I heard the Rambam wrote), BUT at the same time they have a big problem mainly with 2 things- stealing (like everyone else), and most of all Murder, if they support, or cheer or are even happy with murder they are held accountable. So technically all of the hamas-hezbollah, etc. crowds are Hayav Mita, and if they are killed (by us) we are not responsible for their blood.
BUT technically if their is a Muslim, who does not like to see for example Jews being blown up in buses, etc. Doesn't get a good feeling about it, doesn't support the terrorists and murderers in anyway (knowingly). Believes in G-d, doesn't steal, etc. Then they could be a Noahide in some opinions, and in another, maybe still not because a Noahide has to do soo in front of a Beit Din, and declare that they are doing it becuase G-d wants it, and not because the commandments are logical (but even a Muslim could maybe fall in this category) BUT, then another opinion might say still no, because a Muslim in essence could see himself as replacing the Jewish nation, etc. and the true G-d, is the G-d of Israel. So if a person is a noahide they cant have another religion to themselves because having another religion in essence says that they are replacing the G-d of Israel.