Just a note on 2 John 8-11
:The person that a Christian would not say 'greetings' (Greek = 'chairo' = 'rejoice/be well/thrive') would be one who does not "remain in the teaching of the Christ", not one who disagrees with certain interpretations of Scripture.
And Titus 3:9:
Here, persons rejected are those involved in "foolish controversies" about genealogies and the Mosaic law, the reason being that these are "unprofitable and futile". Thus divisions could be caused through unnecessary debate about obscure and unimportant matters. It is obvious that this has nothing to do with genuine legitimate concerns over moral or physical dangers to members of the congregation, nor to concerns over potentially harmful interpretations of Scripture.