"Jesus, if you believe the Bible.”If he won’t listen to the church, treat him as a pagan or tax collector.” http://www.catholic.com/tracts/proving-inspiration"
IOWs, the Church says so. Jesus did not say the Church was infallible, nor would He ever endorse such a claim. Your partial quote left out the fact that "the church" spoken of, would be simply deciding to back the some accuser. If what you say is true, then infallibility can be found in democratic action and that proposition is ridiculous.
Also note that proof only applies in mathematics. only evidence applies in all other cases.
That’s your interpretation, and here we are.
Interestingly, if the Church that wrote, preserved and canonized the Bible is fallible, then...
If Jesus founded a Church, which Scripture calls “the pillar and foundation of truth,” is it fallible?
The most significant question begged is the definition of infallibility, which the Church has the authority to define:
http://www.newadvent.org/cathen/07790a.htm