I have a suspicion that the phrase "bad theology" will cause some objection (while "good theology" will go without notice). It's common for discussions of good and bad theology to have no content beyond taking sides and calling names. This has led to some justifiable distaste for the whole venture of separating good and bad theology. But recognizing the good is just as important as it has ever been; the problem is identifying the bad without going overboard and losing a valid perspective or descending into petty partisanship. I intend to sketch out several posts in a series of how to identify good and bad theology without subjecting the system to the judgment of any partisan system's pet litmus test; I hope to sketch out criteria which can successfully separate the partisan systems from the whole and robust systems.
Consider this analogy: I take apart my lawnmower and put it back together. When I am finished, I have leftover extra parts. Looking at the extra parts, I claim to have put it back together better than before. Do you believe me? Or is it possible that I didn't really understand what those parts were for and how they fit into the whole?
One way to recognize a bad theological understanding is by the leftover parts. If there are passages of the Bible that have no place in a theological system, it's a bad system; at the very least it's incomplete. You can guarantee that there is a lack of understanding of those leftover parts, what they were for and how they should have fit into the whole.
A good understanding of God and his kingdom, at the very least, takes into account the whole of the Bible. There are no leftover parts which do not fit.