Islam is an Arabic word and it connotes submission, surrender and obedience. As a religion, Islam stands for complete submission and obedience to Allah (God).
Islam, in fact, is an attributive title. Anyone who possesses this attribute, whatever race, community, country or group he or she belongs to, is a Muslim. According to the Qur'an (the Holy Book of the Muslims), among every people and in all ages there have been good and righteous people who possessed this attribute - and all of them were and are Muslims.
Islam is a universal and eternal religion. Its appeal is to the whole humanity. Any person who declares belief in La ilaha illallah Muhammad-ur-Rasulullah (there is no deity but Allah, and Muhammad is His Prophet) enters the fold of Islam and entitles him or herself to the same rights as those of other Muslims.
Prophet Muhammad (blessings of Allah and peace be upon him) has enjoined us to believe in five articles of faith:
1) Belief in one God Who has absolutely no associate with Him in His divinity;
2) Belief in God's Angels;
3) Belief in God's Books, and in the Holy Qur'an as His Last Book;
4) Belief in God's Prophets, and in Muhammad (blessings of Allah and peace be upon him) as His Last and Final Messenger; and
5) Belief in life after death.
One who believes in these articles enters the fold of Islam and becomes a member of the Muslim community. But one does not become a complete Muslim by mere vocal profession alone. To become a complete Muslim one has to fully carry out in practice the instructions given by Prophet Muhammad (blessings of Allah and peace be upon him) as ordained by God.
Ref : http://www.islamicity.com/mosque/Muslim.htm
