Islam is a religion, but not in the western meaning of religion. The western connotation of the term "religion" is something between the believer and God. Islam is a religion organizes all aspects of life on both the individual and national levels.
Islam organizes your relations with God, with yourself, with your children, with your relatives, with your neighbor, with your guest, and with other brethren. Islam clearly establishes your duties and rights in all those relationships.
Islam establishes a clear system of worship, civil rights, laws of marriage and divorce, laws of inheritance, code of behavior, what not to drink, what to wear, and what not to wear, how to worship God, how to govern, the laws of war and peace, when to go to war, when to make peace, the law of economics, and the laws of buying and selling. Islam is a complete code of life.
Islam is not for the mosque only, it is for daily life, a guide to life in all its aspects: socially, economically, and politically.
Islam is complete constitution. Thus Islam keeps the Muslim away from confusion, because Islam is logical and rational. Allah is one. Allah is one Allah has no sons. Allah is not trinity. Allah does not kill to save. No mediation is required between Allah and man. Islam organizes human nature, but does not go against it. There is not a class of clergy in Islam; nor is there celibacy. Islam is complete code of human life.
Reference: The Need for Islam by Dr.Muhammad Al Alkhuli