As far as the Messiah's words at mark 7:18-19, you have to take into account the context of the conversation. The conversation started when the Pharisees and scribes noticed and pointed out that Yeshua's disciples didn't perform n'tilat yadayim, or the ceremonial washing of hands, before eating, which is still performed by Orthodox Jews today (as told in verses 3-4). Yeshua rebukes them for equating the traditions of men; ie, the rabbinical additions to Torah, with Torah law itself, and even elevating the traditions over Scripture (verses 6-13). Afer this He states that nothing that goes within a man can make him unclean, only what comes out of him. They're not speaking of what's permissible to eat; that would be INCONCEIVABLE to the Pharisees and scribes, and so even if it was Messiah's message, He would need to state it specifically, because they would never assume He would insinuate that un-kosher foods are clean
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Well, speaking of context:
You are correct that what caused the conversation to start was the unclean hands comment, but...
Jesus replied with text:
‘(H)This people honors Me with their lips,
But their heart is far away from Me.
7 ‘(I)But in vain do they worship Me,
Teaching as doctrines the precepts of men.’
and parable:
9 He was also saying to them, “You are experts at setting aside the commandment of God in order to keep your (K)tradition. 10 For Moses said, ‘(L)Honor your father and your mother’; and, ‘(M)He who speaks evil of father or mother, is to be put to death’; 11 but you say, ‘If a man says to his father or his mother, whatever I have that would help you is (N)Corban (that is to say, given to God),’ 12 you no longer permit him to do anything for his father or his mother; 13 thus invalidating the word of God by your (O)tradition which you have handed down; and you do many things such as that.”
The Heart of Man
14 After He called the crowd to Him again, He began saying to them, “Listen to Me, all of you, and understand: 15 there is nothing outside the man which can defile him if it goes into him; but the things which proceed out of the man are what defile the man. 16 [If anyone has ears to hear, let him hear.”]
And after all that he explained to his followers:
17 When he had left the crowd and entered (P)the house, (Q)His disciples questioned Him about the parable. 18 And He *said to them, “Are you so lacking in understanding also? Do you not understand that whatever goes into the man from outside cannot defile him, 19 because it does not go into his heart, but into his stomach, and is eliminated?” (Thus He declared (R)all foods (S)clean.) 20 And He was saying, “(T)That which proceeds out of the man, that is what defiles the man. 21 For from within, out of the heart of men, proceed the evil thoughts, fornications, thefts, murders, adulteries, 22 deeds of coveting and wickedness, as well as deceit, sensuality, (U)envy, slander, pride and foolishness. 23 All these evil things proceed from within and defile the man.”
Seems to me that it was a far greater lesson then simply one of "tradition".