Yep. Stuck.
You believe God wills us to be sick sometimes. You believe God wants to die from disease sometimes.
You believe He has some “purpose” in it. You believe He may want to “learn something” or to “show us something” or something that you would never do. You would rightly condemn someone who did those things to their own children.
God is no “respecter of persons”. He wants all to be saved. To know that there are those that will not be saved (scriptural), but to say that that is simple evidence that He DOESN’T want the whole world to be saved is calling the Word a lie.
But you use the same logic with health and prosperity.
By your faith be it done to you. You shouldn’t have any problem with that.
Let’s leave it at that.
So, then, you're saying God's will is NOT done.
I guess it's all about what YOU want, then. If you like we can leave it at that, but consider the magnitude of the error you are making. Remember the first one who demanded his will.