A pope is the successor of St Peter and guided by the Holy Spirit when he makes a declaration on faith or morals to the universal church. This is called infall

A pope is the successor of St Peter and guided by the Holy Spirit when he makes a declaration on faith or morals to the universal church. This is called infallibility. So that is the answer to your question, and it would be normally the case except this particular pope has lost his office through heresy and he is an antipope according to Catholic teaching. The reason that he is so significant to the world, and the reason that the atheists and the left love him so much is he is declaring that the Catholic faith is not necessary for salvation and he is changing Catholicism to emphasize "social justice" and not sin and morality. Almost everyone can acknowledge that this is a revolutionary teaching and they are heaping praise on him. Even Planned Parenthood posted a big "Thank you Pope Francis" on their Facebook page to him.