The Lord had many angels. He had given Lucifer or Harith as the Koran tells, the fairest figure, pointed him out to a key leading position among the angelic host. He became the ruler of this worlds heaven. Lucifer did his work so well, that the Lord made him the treasurer of Eden.

Lucifer belonged to a tribe among the angels, witch were created by the fire of the desert wind. All angels were created of fire, this tribe was also. But it was made out of a flame of fire without smoke, one who shows in the outer edge of the fire. That explain that they were a little bit special than the other angels. The Koran calls them the Djinns. So, the Lord created the earth. The first to live there were the Djinns.

But they couldn't keep peace between each other. The Djinns killed each other. and the blood covered the ground and soiled it. The Lord sent Lucifer with the angelic host. Lucifer lead the war against the Djinns and drew them away, out to the islands and the mountains were nobody traveled.

That was the time were Lucifer felt that he was something above the others. He had done a great achievement and that he wouldn't forget. Then the Lord created man out of mud, because someone had to live in this paradise that he had made and that the Djinns had to leave. The Lord ordered all angels to obey this human, whom he called Adam. But Lucifer refused. He said: "Shall I, who is one of the most powerful angels, obey this human, which you made of mud?" The Lord replied: "But I made him with my hands? You shall obey all that I have created!" Lucifer was proud and said: "I'm superior to him, I'm older that him and I'm created by of more powerful source. You created me of fire, and him of mud."

This kind of talk the Lord didn't want hear. He got both angry and sour, because the way Lucifer spoke he also meant that he didn't worship the Lord and neither admired his work. And that offended the Lord and his coquetry, because the Lord had never ever tolerated other gods in addition to him self. The Lord acclaimed therefore: "Your arrogance and disobedience will be your fall. From now on I deprive you all your good!" And then he preapitated Lucifer into the abyss. Lucifer became Satan, Harith became Iblis by the Koran. He became the evil force of both the Christians and the Islamic religion. The humans blamed him for all their mistakes.

from: Myths & Legends http://www.mythsandlegends.net/english/index.html