To be pure is to be clean; it is to be free of pollution and unadulterated. "Blessed are the pure in heart, for they shall see God." There is no such promise to those who are not pure in heart. This world is a very unclean place. We are swimming in filth up to our necks all the time. We are bombarded with pornography, profanity, blasphemy, and violence in everything we look at and listen to. There is no way to maintain a pure heart and mind unless we separate ourselves from the fountain of it all. If people who call themselves Christians do not start drawing some lines and backing away from all this social media and filth, this generation is going to be completely lost. "Come out from among them, and be ye separate, saith the Lord..." Flee from Sodom or you will die with them, and so will your children.