Islam is different when it deals with beliefs. Islam has five pillars, listed below, in the order of importance. Though I may be mistaken about two and three, they may be inverted.
(Before I proceed, allow me to note that I am not a Muslim, but I’ve studies these things in school)
First, the Shahada/Shahadatayn (the testimonials): There is no god but God, and Muhammed is the Messenger of God. Anyone converting to Islam has to make this statement before a sheikh nowadays. But, in terms of doctrine, it suffices to say this, even to yourself, to be a Muslim. If you are to say this before another Muslim he/she has a duty to treat you as one of the brethren.
Second, the five daily prayers. A Muslim is supposed to perform five prayers a day. The duration of each is between four to ten minutes. If one misses a prayer, one may compensate during the next.
Third, fasting the holy month of Ramadan. A Muslim is expected not to have any food or drink from dawn to dusk, for the duration of the month. Traditionally, this is a month to purify the body and sympathise with the less priviliged. Muhammad broke his fast with water, dates (the fruit you pervs), and yogurt/milk. A cook may taste the food being prepared for iftar (the meal at dusk to break the fast). Children age seven and over are trained to fast slowly, first fasting till noon, then progressing until they can last the entire day with no food or water.
Fourth, Zakat, or almsgiving. A Muslim is supposed to contribute a certain amount of his/her income to charities or directly to the poor. The calculation of the actual amount is rather complicated, and differs by denomination.
Fifth, Hajj, the pilgrimage to Mecca, for those who have the means to perform it. It is not mandatory if you, for reasons of health, finance, or some other valid reason, cannot visit Mecca. Though that visit will absolve you of your sins and allow you to start anew with God. NOT comparable to born again Christians.
Now, stories of the saying and deeds of the prophet (Hadeeth and Sunna, respectively), shed some more light on the matter. In one story, Muhammad is reported to have visited the deathbed of a relative that has nonetheless been a long time enemy of the Muslims. The man asks to be forgiven, and whether or not he will go to heaven or hell. The prophet is said to have asked him to repeat the Shahada (testimonials), thus permitting his entrance to heaven. Accordingly, one concludes that it suffices to firmly believe in God at your deathbed and ye shall be forgiven. God is referred to, at the start of every verse in the Qu’ran, as the Merciful, the Compassionate. He’s supposed to have 99 names, each describing one of his attributes.
However, Islam also emphasises deeds. In another story, two men visit Muhammad, to tell him of a third that was so pious as to spend his days fasting and his nights praying. Muhammad asks, ‘who brings him his food?’. ‘We do’ came the reply from the men. ‘Then your reward with God is greater than his’. This is used to demonstrate that a good Muslim works and performs his/her functions in society, not just worships God. Hence the absence of a monastic tradition in mainstream Islam, though Sufis are a different matter worthy of deeper discussion. I do not know enough about the subject and any help is appreciated.
So, in Islam, belief is critical. You must believe that God is one, and that Muhammad is His Messenger. But, some tradition has it that Muslims may still go to hell, and that belief on its own does not suffice. Though no Muslim will be doomed to eternal hell. Actions are as important as what you profess to believe, but are judged according to intent not consequences.
As I said, I am not a Muslim, and my memory may be a bit rusty. Corrections are welcome.