“Why must these leftists insist upon foisting their bizarre beliefs upon the faithful of an established religion, that rejects their perversions?”
The simple answer is that liberals want a power base from which to operate. They have a hard time creating a decent, stable one on their own so they prefer to be like a parasite and use another group’s power base. A couple things come to mind for me (and since I’m nursing a headache right now, that’s about all I can muster right now), first, the Vietnam War caused a lot of draft dodgers to go into seminaries to avoid serving and as they delved into those schools, they saw that congregations and religious organizations could be a viable power base for their decidedly non-religious aspirations; second, when “Billlyyyons” Carl Sagan was alive, he wrote an article imploring pastors to turn over to him and his acolytes their congregations so they could be properly taught Sagan’s liberal views. The Catholic Church is still a viable power case and so will continue to be a target of leftists who want the power without having to create and sustain it themselves.
Bravo.
This is precisely what The Church has been battling and dealing with for centuries. The liberals main goal is destruction and demolishment. The latter won't happen but they are putting up a fierce battle nonetheless.