One of his friends (not mutual with me) responded thus: I'm kind of missing the message in this status . . . I mean, honsetly I'm seeing it pretty much the same as I would see:
"If you rejected Hitler, you couldn't help but see the Nazi regime as a group in control of a country with an evil dictator and a chronicle of blood and violence."
My friend asked him to clarify, and he said (with obvious errors corrected): It just seems like, by that logic, any group can justify its beliefs and the actions of its leader by simply saying "well you wouldn't understand 'cause you're not one of us."
It did not seem right for me to respond in length on a status which was not mine to a friend I did not share, so I decided to post my "would be" response here.
There is a sense in which every belief system has the power you have mentioned. Any adherents to a worldview (such as National Socialism) can defend that worldview using their own presuppositions and be perfectly justified in their own minds. The cracks are sealed and every horrifying action is justified by their beliefs. It is the perfect circle of logicality which Chesterton described. We, on the other hand, can see the system and see precisely where it falls down because we are out of the system. From this position we can rightly condemn National Socialism on every point in which it deviates from the Law of God. Christianity is similarly closed, with one important difference. It closes around the entire world. The power of the Nazi party was constrained to a few European states (and that for a short period of time) and is now limited to a small number of National Socialists worldwide. If Christ is who He claims to be (which Christians believe), then he lays legitimate claim to the entire world. It is not possible to step out of the world and judge its creator. So, yes a Christian can defend the Old Testament based on His belief in Christ.
I sense an objection. You, I assume, do not agree to my presuppositions. You do not believe that Christ is creator and redeemer and therefore you do not recognize His claim. This would seem to make the argument meaningless. Actually, this fact is regrettable but it does no damage to the argument at all. It still remains the case that Christ’s claims are infinite and, indeed, belief in Christ is essential to seeing the Old Testament rightly. Moreover, we as Christians have legitimate reasons to believe in Christ’s claims. You may continue to judge the actions of a being you do not believe in (this seems to me a worthless endeavor), but you may not compare Him to Hitler or His followers to Nazis. The distance is simply too great. It is quite easy to step out of the tiny domain Hitler claims for himself and judge him from there. It is quite impossible to step out of the domain Christ claims.