First off, the request implies that we can influence Catholic theology. Face it: Christians believe they are right and we are wrong. They think we should convert, and that attitude will not change until Moshiach comes.
And speaking of Moshiach, if we are going to sit down with the Vatican to negotiate liturgy, should we, l’havdil, offer to take out the second paragraph of Aleinu, in which we pray for the day when gentiles will stop worshipping idols? How about “sheheim mishtachavim” – the line that Christian censors removed from Aleinu, claiming it insulted Christians? Many of us have put it back. Should we allow the Vatican to dictate what we say in our prayers? Or should we, perhaps, do a line-by-line analysis of the Talmud to make sure there is nothing there that people may find offensive?
I don’t mean to suggest that we shouldn’t be talking to Catholic leaders. The pope needs to know, for example, that it is good to encourage his millions of followers to support Israel and that it is bad to hate Jews. There needs to be careful dialogue, but it needs to be a secular, common, needs-based dialogue. We should not be studying Talmud together and we should not be discussing prayer.
A Catholic doctor once came to visit me in my office. Someone had told him what I said in a sermon about the murder of pre-born children, and he determined that he and I were on the same page. He invited me to participate in a symposium on abortion, to be made up of doctors, lawyers, and clergy. He was looking for non-Catholics. “After all,” he reasoned, “we orthodox people have to stick together!”
I declined the invitation.