The problem as I see it is that this whole “obey the law” argument completely ignores Romans 8 (as Paul himself often did in some of his other writings). Paul writes that it is only when the law of sin and death is abrogated as the law that the spirit of life takes over in our hearts and minds, affirming to us that we are Children of God. Only then do we even have the capacity to “obey the law,” because it is the Law of Love we are “obeying,” not the law of letters and rules. Oddly enough – and this is a mark of the “wisdom of God” that is “foolishness to those who are perishing” – when the Law of Love is obeyed, obedience to the moral law is what results; whereas our attempts to obey the moral law alone without the aid of the spirit of life who infuses God’s love into our hearts are doomed to failure.