Jehovah is too good to be unjust.

He is too wise to make a mistake; he is too loving to be unkind; and his power is always exercised in such a way that ultimate good may result.
[40]The manifestation of justice is one of the strings upon the harp of God; but we must see and appreciate it in order to understand the beauty and harmony it brings when used in connection with the other springs.
[41]Good and evil are antagonistic principles or rules of action.

Good is the law or rule of action by which God is always governed.

Evil becomes active only when some creature of Jehovah violates his law.

God made man a free moral agent.