There are of course many objections to such a view (see chapter 4 of my book The Truth about God). Here, however, I want to point out one rather interesting consequence of accepting this solution to the problem of evil – a consequence that its defenders are apparently unaware of: namely, that it makes worrying about our moral choices entirely pointless.
Suppose I'm pondering whether or not to perform some terrible act – say, shooting someone in the middle of Fifth Avenue, or perhaps voting for Donald Trump. According to the view in question, if I go ahead and do anything like that, then what I do will serve a purpose of God's that is for the greater good – and thus, in the grand scheme of things, will be a good thing. That is why God will allow me to perform the act. And this is the case no matter how evil a thing we're talking about. But if that's true, then why shouldn't I go ahead and do it?
Now, one apparent problem with this logic is that, even though whatever I do is overall “for the best,” my doing terrible things still makes me an evil-doer – and doesn't that mean I will end up in hell? That is, maybe the things I do will be for the best for most people, but maybe not for me. But, besides being a rather selfish concern, this really is only an apparent problem. For once one realizes that doing these “evil” acts is actually not a bad thing, then one isn't actually doing something evil. That is, if my goal in, say, hitting everyone I encounter on the head with a baseball bat is not to do something bad, but instead to serve God's overall greater purposes (which according to the view is guaranteed to be the case), then how can I be regarded as immoral? It follows that if one agrees with this solution to the problem of evil, then one should no longer be concerned about doing anything bad whatsoever.
Religious people sometimes worry that atheism may lead people morally astray. Will these same people worry about this version of theism?