There are those who don't believe that Satan exists, and in many cases they are the same persons who don't believe that God exists.
But the scriptural evidence supports the existence of both. The whole of the Old Testament assumes the existence of Satan as much as it assumes the existence of God. The book of Genesis is built upon the reality of Satan working through the serpent to cause the downfall of man through sin. Satan is mentioned many times in the Hebrew text and in the Quran.
His existence was recognized by every writer of the New Testament. Nineteen of the 27 books mention Satan by name. There are 29 references to Satan in the Gospels. In 25 of those references, it is Christ who is speaking of Satan, as if he indeed exists.
"The report of the temptation of the wilderness could have come from none other than the Lord Himself, as He described the person-to-person encounter He had with Satan," writes C. Fred Dickason in his book, "Angels: Elect & Evil."
Satan, whose name was Lucifer before his fall from heaven, was probably the highest ranked angel in all creation. God, Himself, referred to Satan as "the anointed cherub" and "the covering cherub," indicating that Satan was a cherub, which scholars today believe to be the highest classification of angels.
The term "anointed" indicates that Satan had a special position with a special assignment.
Ezekiel 28:12-13 says of Satan:
"You were the seal of perfection,
full of wisdom and perfect in beauty.
You were in Eden, the garden of God;
Every precious stone was your covering:
the sardius, topaz and diamond,
beryl, onyx, and jasper, sapphire,
turquoise, and emerald with gold.
The workmanship of your timbrels and pipes
was prepared for you on the day you were created."
The expressions "seal of perfection" and "full of wisdom and perfect in beauty," says Dickason, indicate that Satan was the greatest of all creatures. He was also called the cherub that covers, which refers to his role as guardian and the one who proclaims God's glorious presence and holiness.
The author also believes the line, "... you were in Eden, the garden of God," probably refers to Satan's task in God's paradise in heaven.
Verse 15 continues:
"You were perfect in your ways
from the day you were created,
till iniquity was found in you."
We get a clue of where the iniquity came from in verse 17, which says:
"Your heart was lifted up because
of your beauty;
You corrupted your wisdom for the
Sake of your splendor.
I cast you to the ground,
I laid you before kings."
There are two things the scriptures make clear: Satan is a created being, and that Satan was cast out of heaven for his rebellion. The scriptures seem to indicate that he took a third of the angels with him. Those other fallen angels are known as demons today.
Isaiah 14:12-15 is more specific about Satan's fall. It says:
"How you are fallen from heaven,
O, Lucifer, son of the morning!
How you are cut down to the ground,
you who weakened the nations!
For you have said in your heart:
'I will ascend into heaven,
I will exalt my throne above the stars of God;
I will also sit on the mount of the congregation
on the farthest sides of the north:
I will ascend above the heights of the clouds,
I will be like the Most High.'
Yet you shall be brought down to Sheol,
to the lowest depths of the Pit."
Somehow Satan, or Lucifer, had deluded himself into thinking that he could unseat the Most High God, but he had made a grave error.
Jesus said in Luke 10:18, "I saw Satan fall like lightning from heaven," indicating how fast Satan was kicked out from the presence of God. The name Satan is variously translated as "the accuser" or "the adversary." He is believed by Christians and Jews to be the author of all kinds of evil, including murder, temptation, pride, slander, sexual sins, perversion, division, lying and all forms of deception, and even the antichrist. The scriptures says that God is love, but Satan's ultimate goal, through various entanglements, is to lead humans away from God's love.
In Islam, Satan is referred to as Iblis, and by the Arabic adjective Shaitan. According to the Quran, he disobeyed an order to bow down to Adam, representing God's highest creation, man. For that rebellion he was forced out of heaven.
Islam, Judaism and Christianity seem to agree that Satan, the devil, by whatever name he is called, must face a great final judgment from which there will be no release or forgiveness.