There are many questions concerning Satan the Devil: who is the devil, where did he come from, why did God create him, and why did God not destroy him?
Who is the devil, where did he come from and who created him?
Satan the Devil was created by God just as He created billions of spirit creatures or angels. We do not know the name of the devil, as neither Satan nor Devil are names. Both words describe an evil trait about this spirit creature.
Satan the Devil was originally a faithful servant of god and was such for an interminable periodof time. Somewhere along the way, he became unhappy with his privilege of service and became envious of God and decided to rebel against his Creator.
What exactly happened can be illustrated by parents that have a number of children. The parents teach the children honesty and responsibility. One day, one of the children starts to steal and is branded a thief. Who made the thief? He made himself a thief when he decided to steal.
The angel, whatever his name was, started to go against (resist / satan) God and slandered (slander / devil) God and thus made himself Satan the Devil. (See Genesis 3:1-5)
Why did God not destroy the devil?
God could not destroy the devil right away as he
This can be illustrated this way. Suppose someone comes to you in front of all your friends and accuses you of some criminal acts and calls you a liar. If you quickly took a gun and shot him dead, what would your friends think? Your friends might think that you were trying to silence someone that knew you had done the vile things of which you were accused.
If in time you were able to prove that all the accusations were just lies from someone that was trying to destroy your good name and reputation then you could justifiably incriminate him and have him arrested or even executed when the truth came out that he was the one responsible for the criminal acts. (See Job chapters 1 and 2)
Satan the Devil is responsible for much of the evil on the earth. Soon his time will run out as God proves himself innocent and then the guilty one (Satan the Devil) can be dealt with in all justice. (See book of Revelation)