My biggest struggle with Reformed (Calvinist) theology came when I ran across how most leading thinkers in this tribe dealt with the problem of evil. Why?
Influential Reformed thinkers propose one of two alternatives in regard to this vexing issue: (1) According to the Bible, God ordains all things, including evil, for mysterious reasons that He has not revealed to us but it is part of His perfect plan; or (2) God ordains evil but He cannot be held responsible for wicked acts because they are carried out by sinful humans who are the intermediaries justly held responsible for their actions. The latter argument was popularized by the late Gordon Clark in his book "God Evil, Problem Solved."
These arguments have not exactly blown the skirts up contemporary philosophers of religion. They tend to give more credence to Alvin Plantinga's "Free Will Defense" (which I'll unpack at a later date).
However, it is worth noting that many Reformed apologists (aka "presuppositional apologists", which I'll also address with a later blog post) have fared well in sparring with atheists in public debates. For example, take the time to watch "The Great Debate" between the late Dr. Greg Bahnsen (the Calvinist) and Dr. Gordon Stein (the atheist) on Youtube or listen via a podcast. The problem of evil is only briefly addressed near the end but it is helpful to review. Dr. James R. White has also utilized the Reformed argument in debates as well.
It is also worth taking the time to read Dr. Clark's book, which I mentioned above. I would also recommend "Calvinism and the Problem of Evil" edited by David E. Alexander and Daniel M. Johnson.
That's it for now. Tune back in regularly for more. God bless.