"Is it possible then that the Church has begun to teach error? Can we believe that the one Ark of salvation is at the same time also an instrument of perdition for souls? That the Mystical Body separates itself from its Divine Head, Jesus Christ, making the Savior’s promise fail? This cannot, of course, be admissible, and those who support such an idea fall into heresy and schism. The Church cannot teach error, nor can her Head, the Roman Pontiff, be at the same time heretical and orthodox, Peter and Judas, in communion with all his predecessors and at the same time in schism with them. The only theologically possible answer is that the Conciliar Hierarchy, which proclaims itself Catholic but embraces a faith different from that constantly taught for two thousand years by the Catholic Church, belongs to another entity and therefore does not represent the true Church of Christ."
This is the stumbling block for many NO and "conservative" Catholics trying to make sense of the crisis, the answer of which is succinctly stated.
The Conciliar Church is not the Catholic Church.