“We know that ALL things work together for good to those who love God, to those who are called according to His purpose.” (Romans 8:28)
A thing compared to itself cannot be fully known or appreciated until it is compared to something else. It is the contrast of one thing to another that makes the superior thing better. Ugliness makes Beauty more beautiful. Rotten food makes fresh food more delicious. Monochrome makes a rainbow more colorful. Darkness makes the Light brighter. Evil makes Good more virtuous.
It is the same with God.
Satan, evil, sin, suffering, and death all work together to make God more glorious, desirable, beautiful, radiant, and superior. Without evil, we could not comprehend God’s goodness and we would have no Good News. We would not know what should be or what could be. We would only know what is. Without evil, we could love God, but our love would be shallow. We wouldn’t run to Him, we wouldn’t cling desperately to Him like we do, we would not appreciate all the goodness that is in Jesus Christ. We wouldn’t long for His coming.
So then, is evil good? Is sin good? ABSOLUTELY NOT! Evil is still evil. Sin is still sin and contrary to God’s will. So why is there evil in the first place? Why does God allow evil to exist? The short answer: He uses evil to accomplish His purposes, and His purposes are ultimately good. You see it all throughout the Bible. Think about the ultimate evil done to the most innocent person who ever walked the earth, Jesus Christ. God allowed this to happen so that He could bring about the greatest good to mankind, salvation!
So then, is it good that sin and evil exist? Yes, for through them we are witnesses to God’s goodness, his mercy and grace, and we experience His love as superior to anything else we can find on earth.