"Islamic" means that it is related to the religion called "Islam". Such countries had, and still have, a population which, in their majority, was islamic.
Called Imam
Kh'elafa:
Muslims
It is called a Mosque
Muslims
Tecnically, the religion is called Islam and the people that follow the Islamic religion are called Muslims, so yes, being a Muslim counts as a religion.
Yes he is called Allah.
The people who have belonged Islamic religion are called Muslims.
He was an Israelite. They were later called Jews.
Followers of Islamic religion are called Muslims.
The answer is in your Question: Islam and its followers are called Muslim