Here you have alluded to the question of free will vs. predetermination that we seem to be on different sides on.
Now to make my position clear, I do think that there is what you call God's will. I see it manifesting as the correct path to take in life. But what I also see is that humans, at least, have the choice to take the correct path or go astray. Often it is not clear what the correct path is.
Let me exemplify by the experience of a close relative of mine. She recently got a PhD in a relatively small research field, less than 50 active academics in the country. She was also the only one to get a job offer in her graduating class, but it meant going to a part of the country that was not appealing to her. At the same time in her heart she wished to join a religious organization at considerably less compensation and essentially givin g up her well earned status in the research field.
She decided to take the position as Professor and pay her dues in this field, and later switch to a more attractive area of the country. But after going to be a professor she found that it was even worse than she expected and over the years suffered physical distress as a result. No need to provide any more details, but she is still making choices that will impact the rest of her life.
So what I see is akin to the covenant of the old testament. Each of us has a path that is optimum in the eyes of God, so to speak. But that path is unknown to begin with. If we make the right choices along the way, which to my mind is just following your heart, we may not end up rich, but we will end up healthy and happy. And it will not even be clear that we made the right choices. It seems you only find out if your choices are off path.
So there is a kind of predestination except it is up to each of us to find our own destiny. If everybody did that well, then God would know the outcome from the outset. But poor choices, what normally is called evil, can intervene, and make prediction of the future inexact, even for a god.
So besides all the above, I see evil as necessary for free will. Evil may have many other functions, like promoting evolution by selection of the fittest warriors. But if there is true predestination, then there is difficulty explaining much of the history of the world as consistent with a benoviolent God.
Intelligent design is apropos here. But that is a new thread.