Winthrop gave speeches and published lectures on established Puritan doctrine in an effort to counter the influence of Antinomian supporters in the colony and justify the trial and eventual exile of the woman seen as the leader of these dissenters, Anne Hutchinson.
They seem very wary of any outsiders including Native Americans because it almost feels as if they are threatened by their actual presence. Any outside interaction is almost a viable threat to their society and views.
I feel this idea comes with Tyranny a lot as well, just the idea that these ideas are superior, you must follow them and that no other outside knowledge will be allowed.. kind of like North Korea. Puritans had it set up this way due to their strict social hierarchy.