When we walk into heaven, we are going to be surprised at who is- and isn't there.
Outside of Christ there is no salvation. If you are in Christ, by grace through faith, you are, by definition, the Church.
So what then of the righteous Jew? The righteous Muslim? The Hindu? The (gasp) righteous atheist?
Those are both good points. The only Scriptural picture we have of the Final Judgment is Matthew 25, and it portrays EVERYBODY, both the saved and the damned, as being surprised: "LOrd, when did we see you hungry?"
A little odd, but there it is...
And your other point is interesting, in terms of a definition of the Church. We Catholics believe that the true and original and only Church founded by Jesus Christ "subsists in" the Catholic Church. But that term "subsists in" is maybe (sigh) a little subtle? (And this is a notoriously hair-splitting Church, one that knows what "is" is!)
Bottom line, as our esteemed Orthodox brethren put it, "We know where the Church is; but we don't know where the Church is not."
That's one reason why the Church will formally canonize, but never formally "demonize." We know for sure that some people are in heaven because of their Catholic Faith, their life of heroic virtue, and confirmed by 2 miracles (these are the formal requirements for canonization.) But we daren't say for sure that anybody by name is damned. We just don't have God's perfect knowledge of the inner person, nor God's perfect justice, nor God's perfect will to save.
Nothing but the blood of Christ is necessary to salvation.
Perhaps he will also bring up the mystery of Christ and the church being a marriage.