1st Kings 21:29
“Do you see how Ahab has humbled himself before Me? Because he has humbled himself before Me, I will not bring the evil in his days, but I will bring the evil upon his house in his son’s days.”
According to Calvinism, apart from the miracle of regeneration, fallen man cannot take even one step towards pleasing God in the flesh. Therefore, to what will Calvinists attribute Ahab’s humility that pleased God? Ahab was certainly not part of Calvinism’s elect, and hence was not a candidate for regeneration. The only way that this makes any real sense is if Ahab could have either chosen to humble himself or not, and by making that right choice, God received glory and withheld His judgment.