No they are not. Perhaps some of their ancestors were, but this is now THEIR religon, and they have a right to practice it, no matter what someone thinks about about whether Indians shouldn't be Christian or not for whatever reason.
Who said anything about stopping the practice of it? Catholicism is not taught in US public schools, either, but the practice goes on.
Do we teach Christianity in taxpayer funded schools on the Navajo reservation? The answer is no.
Why should Bolivian indians, who are in the majority, be taxed to pay for indoctrinating their children in a foreign, European (last I heard, the Vatican was still in Europe) religion.
Now that the Bolivians have an Indian president, and an Indian majority, what is so alarming about tossing the yoke of a state church, which, if it's such a great thing, maybe you'd like to see in America.
Think before you answer though. Having a state church has so secularized France that religion's nearly dead there.
But then, they had the Enlightenment to help things along. Maybe Enlightenment's finally reaching the western hemisphere in one form or the other.