The second largest world religion
and growing.

Common beliefs:
Strict monotheism. God is the creator, is just, omnipotent and merciful
Respect for earlier prophets and belief in their teachings: Abraham, Moses and Jesus (peace be upon them).
That Mohammed (pbuh) is the last of the prophets
Belief in the existence of Satan who drives people to sin
That Muslims who sincerely repent and submit to God return to a state of sinlessness
Belief in Hell where unbelievers and sinners spend eternity. One translation of the Qur'an 98:1-8 states: "The unbelievers among the People of the Book and the pagans shall burn for ever in the fire of Hell. They are the vilest of all creatures." ("People of the Book" refers to Christians, Jews and Muslims
Belief in Paradise, a place of physical and spiritual pleasure where the sinless go after death
Abstinence from alcohol and gambling
Rejection of racism
Avoid the use of alcohol, other drugs, eating of pork, etc.
Avoid gambling
That Jesus (pbuh) is a prophet. They regard the Christian concept of the deity of Jesus (pbuh) to be blasphemous
That Jesus (pbuh) was not executed on the cross

Originally, in Islamic countries, there was no separation between religious and civil law, between Islam and the state. Turkey and some other countries have become secular states during this century. This is a controversial move in Islamic circles.

Understanding of Jesus (pbuh), within Islam and Christianity:

Traditional Christians and Muslims have certain beliefs in common concerning Jesus (pbuh). They both accept that:
His birth was miraculous.
He was the Messiah.
He cured people of illness.
He restored dead people to life.

However, they differ from Christians in a number of major areas. Muslims do not believe
In original sin (that everyone inherits a sinful nature because of Adam and Eve's transgression)
That Jesus (pbuh) was killed during his crucifixion. Muslims believe that he escaped being executed, and later reappeared to his disciples without having first died.
That Jesus (pbuh) was resurrected (or resurrected himself) circa 30 CE.
Salvation is dependent either upon belief in the resurrection of Jesus (pbuh) (as in Paul's writings) or belief that Jesus (pbuh) is the Son of God (as in the Gospel of John).

Schools within Islam:
There are different schools of jurisprudence within Islam. The main divisions are:
Sunni Muslims: These are followers of the Hanifa, Shafi, Hanibal and Malik schools. They constitute a 90% majority of the believers, and are considered to be main stream traditionalists. Because they are comfortable pursuing their faith within secular societies, they have been able to adapt to a variety of national cultures, while following their three sources of law: the Qur'an, Hadith and consensus of Muslims.

Shi'ite Muslims: These are followers of the Jafri school who constitute a small minority of Islam. They split from the Sunnis over a dispute about the successor to Mohammed (pbuh). Their leaders promote a strict interpretation of the Qur'an and close adherents to its teachings. They believe in 12 heavenly Imams (perfect teachers) who led the Shi'ites in succession. Shi'ites believe that the 12th Imam, the Mahdi (guided one), never died but went into hiding waiting for the optimum time to reappear and guide humans towards justice and peace.

Sufism: This is a mystic tradition in which followers seek inner knowledge directly from God through meditation and ritual and dancing. They developed late in the 10th century CE as an ascetic reaction to the formalism and laws of the Qur'an. There are Sufis from both the Sunni and Shi'ite groups. However, some Sunni followers to not consider Sufiism as a valid Islamic practice. They incorporated ideas from Neoplatonism, Buddhism, and Christianity. They emphasize personal union with the divine. In the Middle East, some Sufi traditions are considered to be a separate school of Islam. In North and sub-Saharan Africa, Sufism is more a style and an approach rather than a separate school.

Unlike Christianity, Islam does not have denominational mosques. Members are welcome to attend any mosque in any land.

Bahai
A relatively new world religion, the Baha'i faith attempts to unite all humanity in the belief that there is only one God.
It began when a young man announced that a new messenger of God would appear.
Unfortunately this announcement was made in Iran a very Muslim state,
and the young prophet Bab was executed along with thousands of his followers.
One of his followers, a member of a wealthy family was banished to Iraq and eventually imprisoned.
While imprisoned he realized that he was the messiah that his former leader was speaking of. While in prison Bahá'u'lláh which means Glory of God spread his inspirational message to his followers through extensive correspondence. After his death in 1892 his successor took the faith to other parts of the world as a missionary. The Baha'i faith has it's roots in Islam as they believe in one God but rejects some of the teachings of Muhammad such as the practice of polygamy and slavery.
The Bahais principals are summed up as:

Bahá'u'lláh led a group of people in a time where the present religion of Islam seemed to stagnate. A new modern world seemed to beckon on the horizon and a new prophet would lead the way to unite mankind.