Mohammed receiving revelation from the angel Gabriel
From the book Jami' al-Tawarikh by Rashid al-Din, published in Tabriz, Persia, 1307 Now in the collection of the Edinburgh University Library, Scotland, Public Domain
Islam emphasizes that God is perfectly one. He was not created by any other being, nor has he had any offspring. He is completely unique, completely transcendent, and nothing compares to him. The basic statement of faith for all Muslims begins, "La ilaha ila Allah" (There is no God but Allah). There are no other gods, no other divine beings, nothing to associate with God or compete with him. Islam does believe in angels, including wicked angels with Satan as their leader, but they are creatures of God, created just as humans are. People and jinn are intelligent beings, people created out of clay and jinn created from smokeless flames. Angels, created out of light, are not intelligent beings in Islam.
Unlike humans and angels, jinn are imperceptible. They can take many different forms, and are capable of performing heavy labor and difficult tasks. Muhammad was sent to bring God's revelation to the jinn as well as humans, and the jinn will be judged just as the humans will be. Some will spend eternity in heaven, while others will be cast into the eternal fire.
The most famous angel is the archangel Gabriel. Gabriel is the divine messenger who reveals divine mysteries and delivers God's orders and aid to the prophets. Muhammad taught that it was Gabriel who brought him God's revelation. There are many different legends about Gabriel in Muslim tradition, many of which overlap with biblical traditions about the patriarchs and the prophets. Gabriel is said to have consoled Adam after the expulsion from paradise and taught him the letters of the alphabet, how to cultivate wheat, and how to make tools from iron. It is also said that Gabriel took Adam to Mecca and taught him the rites of pilgrimage. He showed Noah how to build the ark, and had numerous encounters with Abraham. He helped Moses fight the magicians of Egypt, and goaded Pharaoh's army into the Red Sea. He taught the prophet Samuel, and comforted King David. And he announced the coming birth of John the Baptist to Zacharias.
Satan, or the Devil, is called Iblis. Satan is one of the jinn. The Quran tells the story of his role at the beginning of the world. God formed Adam out of the earth, the Quran reports, and then breathed life into him. Then God ordered the angels and Iblis to prostrate to Adam. Iblis refused. He was created of fire, and considered it beneath his dignity to bow to a creature made of earth. God cursed him and banished him, but he begged God to delay his banishment until the Day of Judgment, and God agreed. While they were still in paradise, Iblis tempted Adam and Eve to eat the forbidden fruit. Iblis was also granted the power to tempt other creatures, allowing him to expose those who are not true servants of God. Iblis has gathered followers along the way, and at the end of the world, he will be thrown into the eternal fire along with all his followers and all those judged to be wicked. Until the world ends, Iblis will play tricks on humans and lead them astray. Only the believers will remain firmly committed to God.