Outside of the Bible, itself, this may well be the single most important book I have ever read. I cannot urge people to read this book strongly enough. In fact, for any believer, or anyone who seeks to understand the Scriptures on their own terms, this book should be mandatory reading. I consider it to be that important. If you have not read it, buy a copy today, then make time to read it. It will be one of the most enlightening experiences you will ever have.
Now, there are many who strongly disagree with the argument put forth in this book. Some have gone so far as to call Dr. Heiser a heretic. All I can say to those people is that I disagree in the strongest of terms. I have read Dr, Heiser’s work — carefully. I have followed behind him, both in Scripture and his references. I have read the Scriptures many times. And I have applied my special talent for finding logical contradictions and inconsistencies to the whole process. I can say without any hesitation or reservation that Dr. Heiser has won me to his side. There is absolutely nothing inconsistent with the argument in this book and the Scriptures, themselves. In fact, it is quite the opposite: much of Scripture cannot be properly understood unless we read it from the world view described in:
The Unseen Realm: Recovering the Supernatural Worldview of the Bible
The Oil for Your Lamp 
His arguments against Calvinism have been refuted several times over, so he could do well to stay in his lane in that regard — but The Unseen Realm is a very important book for our times. I came across it while reading “Giants: Sons Of The Gods” by David Van Dorn (another book in the same genre that I highly recommend). There are parts of the book I wouldn’t recommend or agree with, and I would encourage Christians to read with caution in some areas and practice discretion at times, but the crux of Heiser’s argument is hard to disagree with.
Hello, and thanks for the comment. I have not read any refutation of Heiser’s argument against Calvanism, but I don’t really need to do so. I would reject Calvanism, myself, and I would do so based on nothing but Scripture. One must have free will or Scripture is in conflict with itself. Since that cannot be, then we have free will — period! That said, I think Calvin’s dilema is that pre-destination of some sort is clearly in the Scriptures, so he assumed a false dilemma: that we either have free will or we do not. The catch is, logically, it is possible for all of us to have free will and yet, YHWH’s will be pre-destined. You see, it is a paradox, not a contradiction. The difference is, a contradiction cannot be resolved, but a paradox can be. This is why I tend to be sympathetic toward Heiser’s position on Calvanism.
Now, the next point I anticipate is that some may think I am arguing that we can place YHWH in debt to us by our actions. Again, I am not arguing this position, either. Those who think the only options are pre-destination or self-determinism are falling for another false dilemma. In reality, all we have is yet another paradox. The solution to this one is easy. All YHWH has to do before He ever creates a single thing is declare that anyone who chooses to accept His offer of grace will be saved and then, if we chose it, we are saved, but not by anything we did. Yes, we made a free will choice, but that choice would not place YHWH under any obligation. Rather, YHWH placed Himself under the obligation when He set the parameters in the first place. It is the same as when YHWH swears by Himself in making covenants in Scripture. Nothing promised to Abraham, was under Abraham’s control, but Abraham’s faithfulness to YHWH placed Abraham under the covenant YHWH swore to Himself. Abraham had free will, but his actions had no power over YHWH as it was YHWH Who set the conditions by which Abraham was blessed and saved.
Anyway, this is how I have come to understand these issues. No one is under any obligation to agree with me. I just hope I explained it well enough to be clearly and properly understood is all. 🙂