I was pleasantly surprised to see this in the draft constitution for Egypt:
Article 3 The practice of Christianity and Judaism
Persons embracing Christianity and Judaism shall have the right to revert to their respective religious laws in matters relevant to personal affairs, the practice of religious (affairs) or (rituals), and the nomination of spiritual leaders.
On the other hand, there is this (in Art. 2):
Islam is the religion of the State and Arabic is the official language. The principles of Islamic Law are the main source of legislation and Al-Azhar is the final authority in the interpretation thereof.
Article 4 Al-Azhar
Al-Azhar is an independent Islamic authority, headquartered in Cairo, and responsible for the affairs of the Islamic nation and the world as a whole. [...]
(Egypt’s draft, at least the English translation posted, does not yet define the system of government.)