What does "Throwing Pearls to Swine" (Matt 7:6) mean? So This is Christ delivering the 'Sermon on the Mount'. And I think he's talking about how to deal with other people because In the same passage, Christ talks about Taking the beam from your own eye, before removing the mote from your brother's eye. 

The verse directly after: 


  Do not give dogs what is holy; do not throw your pearls before swine. If you do, they may trample them under their feet, and then turn and tear you to pieces. (Matt 7:6)


It seems to say don't preach the Gospel (what is holy, and was is -precious as- pearls) to the Dogs and Swine, which I can only imagine as Sinners. But I don't think that is correct! Because the Lord preached to Sinners, and even said that he came for sinners - and not the righteous. (Luke 5:32) 

So is the (Holy things/Pearls) not the Gospel?

Who are the Dogs/Swine? And How do I know who is the Dog/Swine?
In Proverbs 9.8, 26:1-11 (and many more), the Bible talks about the fool. A fool is characterized as unteachable, therefore unwise in this passage.

The passage tells us that there is no sense to invest into the unteachable. There is only one things you might do: discipline the fool. But still, that does not benefit the fool, but the teachable that watches and takes it to heart.

I always interpreted the dogs and the swines as the unteachable, the fools (for one because of Proverbs 26:11). The holy things and pearls are the pieces of wisdom and truth taken from the word, and certainly include the Gospel.

There is a clear distinction between sinners and fools. Sinners might be teachable, and fools might at a time even have accepted Christ, but are not willing to go deeper and be taught further.

On the other side we are not to judge people. Yet we need to be wise. Proverbs 9:8 tells us that rebuking a fool will have him hate you. That is by no means what we want. Thus, if we find somebody to be unteachable, we stop teaching him. But we certainly do not stop praying for the person.