The word Catholic, the Church says, describes your obligations to see the Church as the truth and support and live that truth. It says it is not to be a boast or a label but an admission of what your commitments should be and what your obligations are. If you say, “I am a Catholic and I believe abortion is not a sin ever” it says that is self-contradiction. You are contradicting what you are and lying that your opinion is a Catholic one. You are Catholic but what you say is not. You are trying to use your Catholicism as a label and to use it to lie with. You are pretending to speak for the Church and Jesus in this matter when you are merely speaking for yourself.

The same idea does not apply to organisations that call themselves Catholic if they object to Catholic doctrine. They have no right to speak for the Church.

Catholic means being open to and inclusive of all who aim for the truth and who believe that truth is objective and not mere opinion.  In that sense, the Church claims that all searches for truth are Catholic.  The secular idea of religion being cordoned off from other things is rejected as there is believed to be no other.  The logic is that God has set up the Church and calls all to join it and be taught by it.  The logic is that all truth comes from God.

That idea by definition bans those who put their opinion before facts or who claim that their own opinion is definitive.  If a religion becomes a hotbed of opinion division will soon be rife.  Catholic implies being committed to letting the truth unite us and that is not Catholic.