[PGalt]

From the factbook...

Muslim 96% (Shia 16%), other (includes Christian, Hindu) 4%

[Cronos]

Do note that the 4% other are people who came there before independence in 1971 and are predominantly of Indian origin. It is illegal to convert from Islam in the UAE

Though, do note that out of the total residents in the UAE, only 15% are citizens -- they have a huge number of expatriates as there is 0 income tax. The majority of these expats are from India, the Philippines,the UK, Russia and Bangladesh and Pakistan