"The heavens, are telling the glory of GOD, And, the work of his hands, the expanse is declaring;" (Ps 19:1 [EBR])
"I form the light, and create darkness; I make peace, and create evil. I am Jehovah, that doeth all these things." (Isa 45:7 [ASV])
Father created for us a daily demonstration of the function of evil (which may be defined as the absence of God)...
The glory of the stars is unknown to the daytime. It is night, or the absence of the sun's light, that allows the revelation their glory. As shown in the banner above, without that backdrop, we would not know the wonders of the heavens. It is darkness, the absence of sunlight, that allows us to perceive the glorious light of the stars. Each evening, as the light of the sun fails, the glory of the heavens is once again displayed.
This daily cycle testifies to the purpose of evil. The very definition of love is the divine response to evil (1 Cor 13). It is evil that provides the backdrop against which Father's unending and overwhelming love is revealed. Without evil, Father's love would have no meaning to us.
What is light without darkness? What is mercy without guilt? What is long-suffering without evil?
Unconditional Love (Father's essence and nature, Light - Good) can be fully comprehended, appreciated and accepted, only as it is demonstrated against the backdrop of rebellion, sin and rejection (darkness, evil). Careful observation will reveal that the creation is performing exactly as Father designed and intended in this regard. When the ages have run their course, every created being will have experienced Father's Love set against the backdrop of their own darkness.
Then, when evil has served its purpose, it will cease to exist. Paul tells us in 1 Cor 15:24-28 that Jesus will yield up the kingdom to the Father who will then be All in all (everything to everyone). Father will no longer be absent from any part of His creation. Father will fully inhabit His creation and evil will thus be banished. Evil, which Father created, will have performed its function, providing the background necessary to reveal Father's very nature.
May we also observe that long after the ages have seen their end, they will seem to us to have been but a few moments, whose sufferings will fade in the overwhelming flood of joy that will be the result.
"For his anger lasts only a brief moment, and his good favor restores one’s life. One may experience sorrow during the night, but joy arrives in the morning." (Ps 30:5 [NET])