Paul says that he is rude in speech.

(II Corinthians 11:6 [KJV]) But though I be rude in speech, yet not in knowledge; but we have been throughly made manifest among you in all things.

And we are to be followers of Paul as he is of Christ.

(I Corinthians 11:1 [KJV]) Be ye followers of me, even as I also am of Christ.

So we are to be rude in speech.

Now being rude in speech is legal and its a good way to get across that people cant just come and force themselves into your life.

Its an exclusion gospel (kjv) rather than a tolerance gospel (modern versions).

Also the book of revelation speaks for being rude in speech in:

(Revelation of John 22:15 [KJV]) For without are dogs, and sorcerers, and whoremongers, and murderers, and idolaters, and whosoever loveth and maketh a lie.

Because if you are nice to people, or try to be nice, you might end up loving and making a lie.

Its the love kill mentality, the loving mask of church people.

Its the "dont say anything bad" curse of church people.