A surge of Moslem fundamentalism is contributing to sweeping political and social change in some Islamic countries, with consequences for the West still only dimly perceived. Islam, the religion that has become a renewed force in world affairs, is unfamiliar to most Americans. Following are answers to some questions raised by the dramatic developments in the world of Islam.

Q. What is Islam?

A. Islam arose in what is now Saudi Arabia during the 7th Century A.D., based on the preachings of the prophet Mohammed. He taught strict monotheism, summed up in the fundamental Moslem expression of faith: "There is no God but Allah; Mohammed is his prophet." This creed is the chief of Islam's "five pillars." The others are daily prayers, taxes on the rich to take care of the poor, fasting and a pilgrimage to Mecca.

Q. Where is Islam the dominant religion?

A. Spurred by the concept of jihad , or holy war, Islam spread before Mohammed's death in 632 to embrace a large part of Arabia. Within the next few centuries, it expanded rapidly through the Middle East, Africa, parts of Europe, China, Indonesia and the Indian subcontinent. An estimated 700 million people are members of Moslem societies today, although the initial identifications of religious conversion with political conquest has faded.

Q. Do all these people form a unified political bloc on the basis of their shared faith?

A. Islam is a supple religion whose tenets are equally at home in Indonesian jungles, Saudi Arabian deserts, Pakistani villages and Senegalese plains. Although Moslems feel a sense of community because of their common religious heritage, the Moslem nations and their problems are widely divergent and Islam is more a rallying cry than a reason for the political turmoil afflicting them.

Q. Do all Moslems believe alike?

A. Like Christianity, Islam is split into various sects. Sunni Moslems generally are considered the most orthodox and their theology grew largely in reaction to schisms. The largest opposition to Sunni Moslems comes from the Shiites. Their sect stems from a split among Mohammed's descendants in which the Shiites contended Moslem rulers should come from the family of Ali, Mohammed's son-inlaw, rather than the Umayyad dynasty that took over in the second half of the 7th Century. About 90 percent of Iran's 35 million inhabitants are Shiites. The Druze and Bahai religions also sprang from the Shiite current, adopting faiths of their own. Other important expressions of Islam include Sufism, an ascetic reaction to Moslem worldliness, and Wahabism, a puritanical strain of Islam that dominates in Saudi Arabia.

Q. What triggered the increase in Moslem fundamentalism now, after all these years?

A. Scholars differ, but most point to two major factors:

The rise in Arab pride, stemming from huge fortunes amassed in Arab oil states and a sense of honor recovered in the 1973 Middle East war. A1 though many Moslems are not Arab -- Indonesia is the most populous Moslem country -- Islam nonetheless is closely tied to Arab culture. The Koran, the Moslem holy book, is written in Arabic and recited in that toungue in mosques around the world. An Arab proverb underlines this, saying: "When the Arabs rise high, Islam will prosper." Using its oil billions, Saudi Arabia is actively promoting the Moslem current. Riyadh's fortune is behind Islamic projects ranging from an institute for propagating the faith to the financing of anti-Marxist Moslem insurgents in Afghanistan.

A reaction to Western influence in Moslem countries, most of it denying the value of traditional Islamic teaching. In many countries, this influence came from European colonial masters and the reaction is mixed with the affirmation of new nation hood. Col. Muammar Qaddafi's emphasis on Islamic values, for example, grows in large measure from reaction to the heritage of Italian colonialism in Libya.

Q. Is the return to Moslem values likely to harm American interests or help the Soviet Union and other communist nations?

A. Not necessarily. The reaction to culture invasion from the West almost automatically includes the United States, however, since so many signs of Western ways are American -- from Boeing jetliners to Coca Cola. But Islam's abhorrence of communism and its atheism also means trouble for Soviet attempts to gain influence in Moslem countries. Attempts to counter Marxist inroads anywhere in the general Near Eastern region form a keystone of Saudi Arabian foreign policy.