God's Purpose in Heresy

Jesus gave us a mission; that mission is to make disciples of all the nations. In order to do this we have to teach the nations. And here we have a problem. We make disciples by teaching people the truth. The problem is that there are so many people out there teaching, not the truth, but falsehood, or heresy ("heresy" refers to teaching which claims to be true and Christian but which is seriously wrong, to the point of endangering the soul of one who believes it).
This makes teaching the truth difficult since The Truth isn't the only game in town; if people want, they can go to a church down the street and get as much false teaching as they like. The sheer volume and accessibility of false teaching seems to retard the process of teaching truth to the nations.