What would you have the Church do?
These people were theologically and Scripturally wrong; they are wrong today. Should we shrug our spiritual shoulders and wave as the heretics and apostates merrily board the hellbound express?
What should the Church of Jesus Christ do when the arrogance and hubris and pride of mankind leads so many of them into Satanic embrace?
I sympathize with you entirely --- but I still don't think it is morally appropriate for the Church of Jesus Christ to launch a bloody crusade against the Vatican to put an end to this heresy and apostasy :)
Preach the Gospel.
Mark 16:15 And he said to them, "Go into all the world and preach the gospel to every creature."
Obviously your parishoners would have to understand what the gospel is, but other churches have done a pretty good job of teaching their members.
What should the Church of Jesus Christ do when the arrogance and hubris and pride of mankind leads so many of them into Satanic embrace?
We keep trying to preach the gospel to you. We pray for the lost. My local Church has a good outreach to RC's and apprx 25% of our membership are former RC's who have been saved. It really is not a complicated process, if they have open hearts we read Scripture together.