During a trip to Malaysia, you'll quickly see that the choice of religion depends on the cultural origins of the people who live in the country.
The State religion is Islam, which is practised by the majority of the Malaysian population. Religion in Malaysiais strictly controlled by the State and the Constitution includes a clause saying all Malaysians are Muslims. It's no laughing matter. For example, Malaysians are not allowed to change or abandon their faith. Doing can result in a prison or even the death sentence!
Religion is practised in an easy going manner and faith is respected throughout the country. There are two Malaysian States, Kelantan and Terengganu, situated to the northwest that are known for being more extreme. Here all Islamic principles are enforced and must be fully respected. So a word of warning to women travellers hoping to visit these regions. You must dress appropriately to avoid being criticised by the local male population. This also applies if you go the beach. If you do hit the beach, you should be fully dressed even when you go swimming - so don't think about donning a bikini.
Although Islam is practised in all the other regions, you'll find that Malaysians don't follow it down to the last letter. There is a certain fusion between ancient beliefs and Islam with regards to religious practice today.
The cultural origin of Malaysia's different populations plays a part in religious practice. For example the majority of Chinese Malaysians practise Buddhism and occasionally Christianity. People of Indian origin are usually Hindu, although they blend their faith with Islam.
Despite the variety of beliefs, what I did find during my trip to Malaysia was a respect for this religious diversity. But it's not all plain sailing. As Islam is the State religion and, therefore, the most popular, non-Muslims have to follow certain rules, even if they are free to practise another faith. For example in Selangor State, there are 35 words from Islam that non-Muslims are forbidden to utter or write, including the word Allah. Any non-Muslim found using these words risks a hefty fine.