Anything God creates is imperfect
Anything that is not God is by definition imperfect.
God, in his omniscience, knows the outcome of everything. It is possible that he permits some evil acts because to prevent them would incur greater evil or prevent greater good.
God, in their omniscience, understands the impact and outcomes of their actions. Therefore, it is plausible that they already act to eliminate evil when they are able to do so without incurring a greater evil or preventing the occurrence of a greater good.
An omniscient and omnipotent God can intervene to prevent evil from occurring. However, they are unlikely to do so if the outcome of the divine intervention would prevent the occurrence of a greater good or cause a greater evil. For example, imagine a situation where God sees a child suffering from leukaemia. In their benevolence and omnipotence, God could intervene and spare the child. But if the child then grows up to become a serial killer, in eliminating one evil, God has incurred a greater evil. Because we can never know the full impacts of divine intervention, it is possible that God prevents evil deeds whenever they can without incurring a greater evil or preventing a greater good. Without God, the world might be a much worse place. Evil and depraved acts that we cannot even comprehend or believe are possible might have emerged had an omnipotent, omniscient and benevolent God not been working to eliminate evil.
The theory is incomplete because it cannot explain how an action attributes a greater or lesser value to evil deeds. Does God decide when and when not to eliminate evil with the end goal of creating the best possible world for all people? Or does God decide when to intervene based on making preventing many ills on falling on one person and making their life miserable? Does God decide how and when to intervene based on what is morally right and morally wrong? For example, if instead of becoming a serial killer, the child grows up to be a morally impeccable person but accidentally kills four people in a car accident. Would it not be the morally correct decision to spare the child from leukaemia, even if it results in the death of four other people? For the argument to be effective, it must incorporate a bridge between good and evil, and morally right and wrong actions. 
Enter the framing of the argument here ...
[P1] God is all-good, all-knowing, and all-powerful. [P2] Therefore, the only evil he would permit would be that which the act of preventing would prompt greater evil or prevent greater good. [P3] Therefore, evil on earth is compatible with an omniscient, omnipotent, benevolent God.
[Rejecting P2] There is no objective way of assessing what would be a "greater" evil.
Enter more information about the argument here ...