I wonder. Over at John C. Wright's blog, he posts a reader who argues that it is. Yes, it had some pretty obvious Christian imagery. That doesn't always mean something is filled to the brim with Gospel messaging.
It wouldn't surprise me if it was. Even if Europe and the West were quickly shedding their beliefs in the Christian Faith by the 20th Century, it was still there. And if belief in the religious message wasn't there, you could still find value in the Faith's teachings and symbolism.
Plus, you have to watch out. Even if it wasn't steeped in Catholic meaning, that doesn't mean it was some communist socialist agitprop, as I've at times heard it (and other things) described. In any event, it has been a long time since I watched it. I'll have to go back and watch it. The last time I saw it the boys were much younger, but all agreed it lived up to the hype.