the way some of you claim to know the character of God and claim to be biblical scholars really amaze me with your answers.
but knowing God who only knows Good and does good things allow an evil being to run rampant? how is a God who is love put you in a world with evil? do you really think so little of God that He would do it just because he felt like it? would you follow anyone who could promise you God things? i know people who can impart God's peace, God's joy, God's healing and ect. would you follow them instead of God if they could promise you these things? why wouldn't you want to follow people who can give you God's best without having to follow a God which lets you deceive yourself into believing what you wish to believe instead of telling the truth? You all claim God is all that is good and yet He sticks you with a killer. you all claim God is a God who heals but there are so many out there that are sick, crippled, diseased, and ect. why isn't everyone healed? is God selfish by only choosing certain people or is God is unable to heal a person because their sin is stronger than God's healing power? you say God is a God of victory but why is it so many are living in defeat? is sin too powerful for God to overcome?
here are your answers listed in your comments
1. God's love- God is a God of love thus as a loving God, He has to dish out holy and righteous punishment. if one sin is enough for the death penalty for us do you think God who is a God who never changes would let satan off on parole instead of giving him his just reward? #1 impossible
2. our love- our love or how much satan loved has nothing to do with it. as the bible teaches we are not saved by works alone. #2 impossible
3. free will- angels do have free will and according to enoch when they chose the wrong path they were sentenced to hell. so if God held them responsible then what happened to satan? it was not free will that let him go. #3 impossible
4. enticement to sin- since God is a God of Justice then to let satan go so he can cause more evil is wrong. for God is going to punish me for my sins then satan should of been punished for his crimes. #4 impossible
5. God needs to be vindicated for man's sake- this is funny. God needs to explain Himself to us

. i would sure like to know what scriptural reference you found this in. #5 impossible
6. mercy- man had to sacrifice animals to cover their sins to receive mercy from God. why would a being already labelled for the lake of fire be given mercy?
7. for God's grace and glory- why would a God who only does what is right release a criminal so God can get glory? that is like saying we are going to release all our inmates on death row just so we can get more glory when we capture them again. #7 impossible
8. our nature to sin- isn't this why we were made new creatures in Christ so we can resist sin as Jesus did? if sin was in our nature then Christ should of sinned too somewhere within His lifetime. i think it is because we are still living according to the flesh and not the spirit. remember according to scripture we have the same nature as God so it is our nature to sin then it is God's nature too to sin. #8 impossible
9. satan is here for a reason- i agree with this reasoning but not for you reasons that you listed. i will explain below.
10. satan will bring judgment- i think we all know that it is Jesus who will judge us and not the devil. #10 impossible
11. God did not want to destroy His own children(satan)- God is going to send mankind who are not saved into the lake of fire. if God can send us there do you think a God of justice would not do the same to the devil and his followers? #11 impossible
12. survival of the finest- if this is true then why keep satan because Jesus has already put the devil under our feet. he is powerless. according to the bible we were made a little lower than God. the bible also tells us that the angels are jealous of us. this does not sound like we are inferior but superior to them. #12 impossible
-the answer that comes closest is God has a reason for letting him loose. now what could be the reason? God is just so it has to be a righteous and holy decision. so let us look at todays world and try and compare. when is it ok for criminals to be set free? they could be found innocent but i don't think satan fits in that category. they could of broken out of prison but i doubt satan could of gotten away from God. could they have gotten a pardon? i doubt it because God does not strike me as a God that lets murders, robbers, and ect loose in heaven to commit crimes so why would He do it by allowing them on earth? the last choice i can think of is an agreement. what if God promised lucifer things the same way God promised us through His Word. similar to a crook giving up testimony on their bosses in exchange for no prosecution from the law. so if God made an agreement with lucifer before he fell then God would be have to honor that agreement or break His Word and we all know that God never lies or breaks His Word. which also explains why satan and his angels are already judged for the lake of fire. satan is trying to take as many of us as possible with him. i believe this is revenge for what God has decided the fate of satan and his angels. the bible teaches that the lake of fire was for satan and his angels and not for us but because of how satan corrupted adam and eve and caused all the sin thereafter has put us in the same place as satan in the lake of fire which is why Jesus came to call us back to himself and those that listen will be able to avert their fate. otherwise their fates are already tied to that of satan.
God bless