The answer lies in the answer to another question...why is Satan still alive even? Why didn't God destroy him in the beginning, so that none of the crap that's been poured out upon mankind for 6000 years would proceed?
The answer to both questions, is that ideas/mindsets/ideologies that are rooted in rebellion (aka Lucifer) must be allowed to play out. God isn't deferring to Sattan's wishes, just merely giving him enough rope to hang himself, and add coals to his head so that in the end, all his arguments concerning the condemnation and guilt, the worthiness of man to die, etc, will be in the end utterly refuted. Satan's rule as prince of the earth will be finally paid to rest and he would have proved himself unworthy to rule through his own actions and ineptitude to govern...and it will be seen and recognised by all.
A thought here. Your question is very good. Most people say, if God is so good, why does He allow evil things to happen. But you say more accurately, why has God allowed the evil one to continue, only to sow more evil? Which he did from the beginning of man in the garden.
Another question might be, why did God allow pride and evil to enter the heart of an archangel in the first place? Since the source of evil was 'created' by Lucifer, who Jesus calls the father of lies (John 8:44) Is this not how God thus created evil? (Is 45:7) and for the time being allows evil to continue in creation?
It is evident that God allows tribulation and temptation and deception to come our way in order to try our faith in Him (Dan 12:10). But does He do so,
because of Lucifer's sin? I.e. Because Lucifer sinned, who was created perfect in all his ways (Ezek 28:15), God is no longer
sure anyone will abide faithful, and so He
must allow the 'test of time' to tell?
I believe love and risk are at play. When you love someone, you are therefore at risk of betrayal. As one man said, it is only your friends that can betray you. You expect it from your enemies.
I dont believe God knows for certain our responses to trials of faith. Scripture says of God,
Now I know Abraham fears God (Gen 22:12), by not withholding his only son. Love is therefore a risk. And greater love is a greater risk. God
risks allowing His people to be tempted, because He
must, else love is not proven. God is love, and so God is bound to allow His love to be tested,
whether He likes it or not, because iniquity was found in Lucifer, and so iniquity might also be found in us.
I believe this is where love is declared greater than faith (1 Cor 13:13). We are saved by grace through faith, but it is love that makes faith sure and eternal. Our love of God, even as His love of us,
grows as we walk with Him (Eph 4:15) (Col 2:19), and as our love grows (so the song says), so do the trials grow greater, along with the greater risks of failure. Nothing ventured, nothing gained. Without great risk there is no great success.
God literally risked all His Creation by allowing Lucifer to sin and to continue as a false angel of light (2 Cor 11:14), and He even sweetened the pot by making man in His own image
in creation. And why? Because He did know of a certainty that the devil would be overcome by man (Rev 17:14), and that man, made in His own image, would choose Him over Satan (Josh 24:15), because He would in the latter days throw all stakes on the table by sending His own Son into the world. Jesus, who is God, was sent as God's ace in the hole to prove once and for all that a man made according to the flesh (Rom 1:3),
would not accuse and reject God after the similitude of Adam's transgression (Rom 5:14). And that man is the man Christ Jesus.
Knowledge, reasonings, learning, etc...may indeed vanish away in the final trial (1 Cor 13:8), but love will be greater at that time, even greater than death. By faith we
know God loves us (John 3:16, I John 4:19), but only by the love of God shed abroad in our hearts (Rom 5:5), can we be sure we will love Him and not our own lives to the end (Rev 12:11). By faith we overcome the world (1 John 5:4), but by love we overcome Satan. By love we stand sure for God and will lay down our life for Him, even as He did for us. (John 15:13)
The reason God allowed iniquity to enter into Lucifer, and then allowed Satan to continue
for a season to make war against us (Rev 6:11, 12:12) is because His love in us wants us to overcome Satan for ourselves, and prove to ourselves and to Him, that we love Him more than we love the creation He created. (Rom 1:25)(1 John 2:15). In this way Satan and his tribulation are become
necessary for us to be tried (Acts 14:22). We ought not want him to be shut up (Rev 20:3) nor to be taken out of the way of His tribulation (2 Thess 2:7), lest we fall short of full trial that proves the fullness of His love in our hearts (Eph 3:19). Paul was torn between two things: A sure road to glory by death, or continued risk of grievance, betrayal, and sorrow in the ministry of Christ. He would remain in the world, because he so loved the believers, even as God so loved the world. The risk was worth the reward, and he was willing to risk it even for Gentiles that were called uncircumcision (Eph 2:11) by his own kinsmen after the flesh. The same as Jesus was willing to risk the cross for mankind that is called
but flesh by His own Father. (Psalms 78:39)
Great trial has great risk, but only great trial can grow great love. And what was the greatest trial of the man Jesus? His wish to be taken out of the way of the cross. (Mark 14:36) He shed blood of prayer
for our sakes, before He ever shed blood on the cross. In the end, Satan may be our accuser (Rev 12:10), but he really is no risk nor match nor great adversary for us. We all shall look narrowly upon him (Isaiah 14:16) as the weakling that he is, so long as we love God as He first loved us in laying down our lives for one another. (1 John 4:9, 3:16)
