The Bible says to "remove the wicked man". The scriptures teach that certain things are "works of the flesh". Some verses speak of "marking" or "taking special notice of" if a congregant is "disorderly".
Where does the Bible teach that a "sinner" should meet with 3 elders and they should hold a "judicial meeting to determine whether someone is repentant oe not"? Where does it say that one shouldn't even say "hello" to a "fornicator"?
How would you show that the Witness way of shunning or disfellowshipping is scripturally incorrect?