I tell you one thing. I definitely know how to get you guys fired up now and giving counter arguments to the Neo-Caths (which is a good thing).
Previously I've posted quotes from Neo-Cath friends and heard crickets chirp waiting for responses. It seems I simply have to present the Neo-Cath arguments myself as devil's advocate and throw some right hooks and the good stuff starts flowing.

You guys raise a good point. He invited them there to pray for peace knowing some of them would pray to false gods. However, Neo-Caths would still argue the Jews (did they attend?) and the Muslims still worship the God of Abraham.
I can foresee Neo-Cath responses along these lines:
1.) These types are praying to God as they understand Him. There is only one God and thus in reality they are praying to Him though they misunderstand the nature of God and thus do not recognize Him as we do. Therefore they are sincere in their attempt to pray to God as best as they can see Him. Thus some reduced culpability must be taken for their subjective state of ignorance and/or error.
2.) JPII preached Jesus Christ at the gathering. He did not force the non-Christians to pray to Jesus, but then again the Church has never taught one should force belief or worship. Instead he tolerated their objectively deficient understanding of the true God in order to bring them together to pray for a common goal, expose them to Catholicism, and work together for good human ends we have in common.