"Do not give what is Holy to the dogs;…"

What do you think Jesus meant by this?

Matthew 7:6(NKJV)

“Do not give what is holy to the dogs; nor cast your pearls before swine, lest they trample them under their feet, and turn and tear you in pieces.

Who are the dogs and the swine?  And doesn't it take a judgement to determine that?

Here is my take on it.  We have a couple of competing commands.  We are to share the Gospel with all and yet we aren't to share it with dogs and swine.  I reach that conclusion based on my belief that the Gospel is Holy.  So how do we handle the conflict?

I think we are to share the Gospel with all unless someone makes it clear that they antagonistic towards the Gospel.  In other words they have shown through word and deed that they are enemies of God. 
 

I think essentially Jesus is saying don't waste your time with people who are actively trying to tear down the Gospel and steal other people's faith.  Let God himself deal with those people.

Make sense?