When Christ said, in Matthew 7:6, "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." he is clearly saying that some (probably many, given Matthew 7:13-14) and not worth the effort.
When you come across people who are swine and dogs, recognise them as such and do not waste your time on them.
When you come across people who are swine and dogs, recognise them as such and do not waste your time on them.