The Law attempts to separate evil from good. But the Law stimulates more evil. Rom 5:20;7:5. Under the economy of grace God recycles evil and uses evil in the creation of good. He wastes nothing. He uses our failures to bring us to the end of the old self (death of ego-centricity), in order to raise up, out of that death, a new self, a new humanity and a new creation. Unlike religion and Law, God never separates out and discards waste; He recycles it. God uses our problems to lead us to the full final solution, glory.
God does not destroy the devil but uses Satan for His own purpose, which is the ultimate victory over evil. This is the principle of the cross. In the economy of grace, Satan has become God's greatest evangelist/transformer, although an unwilling and unwitting one. Satan destroys, kills and scatters. God then recreates, heals, gives life and makes whole and brings it to a level never previously attainable.
In grace, God gives you what you don't deserve. First, He allows Satan to give you suffering and you don't deserve. Then, thru that suffering, God gives you growth and blessings you don't deserve.
For the believer, God perfectly recycles and transforms evil, all mistakes, all accidents, all adversity, all disease and all negative forces into perfect goodness, ultimate good, righteousness, glory and beauty.
When you see God as this Great Recycler, all negative things in your life are caused by God to work together for your good. Ro 8:28. What Satan means for evil, God converts or recycles into good. Gen 50:20. What Joseph's evil brothers meant against him for evil, God meant for good. God recycled it.
God,the Great Recycler!