Because in Mark 7, Jesus teach its not what a person eat that
make a person "unclean", its what that comes out from inside, the
evil thoughts, the sinful desires ...etc that make a person unclean
(ie. not acceptable), cause these are the things that corrupts a
person's heart.
Mark 7:14-23
14Again Jesus called the crowd to him and said, "Listen to me,
everyone, and understand this. 15Nothing outside a man can make him
'unclean' by going into him. Rather, it is what comes out of a man
that makes him 'unclean.' "[f]
17After he had left the crowd and entered the house, his disciples
asked him about this parable. 18"Are you so dull?" he asked. "Don't
you see that nothing that enters a man from the outside can make
him 'unclean'? 19For it doesn't go into his heart but into his
stomach, and then out of his body." (In saying this, Jesus declared
all foods "clean.")
20He went on: "What comes out of a man is what makes him 'unclean.'
21For from within, out of men's hearts, come evil thoughts, sexual
immorality, theft, murder, adultery, 22greed, malice, deceit,
lewdness, envy, slander, arrogance and folly. 23All these evils
come from inside and make a man 'unclean.' "
