Mel is obviously going far out of his way to court evangelicals on this film. The crass-minded would say that he's just building a customer base for his product; but this is clearly a labor of love for Mel. Is he just proselytizing?
How seriously does he believe that salvation is impossible outside the Church? It would be interesting to see someone explore this with him.
Since the manstream press won't, it might be worthwhile for Crisis or First Things or even New Oxford Review to interview him on the subject.
Oh, but he's right in saying that salvation is impossible outside the Church. He's only wrong in assuming he (Mel) knows who's outside the Church and who's inside. :-) Only He (God) knows that for sure.