May i know which Bible you are using that states the para before
7:21 is entitled "false prophets" ? Mine does not say so.
Sure, verses 15 - 20 does state how you can discern false
prophets.
But from verses 21 onwards, I read it also of Jesus giving warning
to us of ourselves rather than just asking us to look out for the
others. That explains my "everyone".
In any case, it is just a comment on your post. Not answering a
particular question.