Even without the Divinely revealed truth of infallibility, we would still know that these current "popes" are not to be followed, nor is their "church" to be joined.
"By their fruits you shall know them. Do men gather grapes of thorns, or figs of thistles? Even so every good tree bringeth forth good fruit, and the evil tree bringeth forth evil fruit. A good tree cannot bring forth evil fruit, neither can an evil tree bring forth good fruit. Every tree that bringeth not forth good fruit, shall be cut down, and shall be cast into the fire. Wherefore by their fruits you shall know them."
And Uriel, I disagree with your position. Good people everywhere?! Catholics must convert non-Catholics, and anyone who refuses to be converted is evil. That's the truth. And those non-Catholics who most appear to be Catholic are the most evil.
Anyone who denies God's words is evil, evil, evil.