I would like to thank you all for answering and thank Rattenhirn for the links.
Upon reading my prior post I realize I did not explain it to well. What I meant was using the Ideologies of these religions in the game. So Islam would not be called Islam, but a person familiar with the religion would have no doubt it is based on Islam. We have multiple people who practice these religions on the team as well as contacts such as religious historians and scholars/judges. We do not plan to be racist and favor any of these religions, but they will each have there own perks in different areas.
For example, if you are in the eastern part of the game world and you don't follow or practice the religion in that part of the world, items from merchant shops will have a heftier tax yet in the part of the world where the religion you follow is dominant you basically can get these items for "cost" price. It will also be a key part of developing land and armies. You can only have certain amount of your troops in certain areas. i.e. unlimited in the christian parts of the world and only 1% in the Islamic or Jewish parts of the world (unless an alliance has been made)
And no you will NOT have to go through the acts of worship or anything. You may go to religious places to ask a priest for a boon for a sum of money but that's about it.
If you guys need any more details or anything just let me know. We plan to put the game plot and such on here but this would not be the correct thread to post it.
EDIT: I should also add that each religion will take you in to a different path of the game, as well as open quests and missions and places that only people of a certain religion can access. Each religion plays an important role in the game plot and none are a negative role.