To rehash the three points  I’ve made about using “rightly” and “proper” to manage interpretations of Scripture:

1.  Using “rightly” and “proper” effectively split’s the community of believers into two camps—insiders and outsiders.
2.  “Rightly” and “proper” are extra biblical means of defining belief in Jesus and Paul‘s letters.
3.  Using “rightly” and “proper” are usually practices carried out by
insiders and it privileges the insider’s camp over the outsider‘s
camp.            

So, in short, talking about “rightly” understanding some piece of
Scripture or having a “proper interpretation” is a way that some
conservative evangelicals manage the abundant possibilities opened up
by the Holy Bible and a way that they sustain their particular visions
of faith.