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, because it does not go into his heart, but into his stomach, and is eliminated?" (Thus He declared all foods clean.) (Mark 7:18-19)
With this first step, Jesus began dismantling the old law in favor of His new one.
There are eight insurmountable problems with this objection:
First, the context of this passage is that Jesus' disciples are eating bread with unwashed hands. They aren't eating ham sandwiches or shrimp cocktail. Certain man-made traditions declared food, even food that was normally acceptable in God's eyes, as unclean if it was eaten with unwashed hands. Jesus was declaring those traditions invalid... not God's commandments declaring certain animals as unsuitable for food. God's food laws were not even part of the conversation in Mark.
Second, if Jesus had "declared all foods clean" then He would be a false prophet. In Deuteronomy 13, Scripture provides the world with a test to determine false prophets: if anyone counsels rebellion against God's commandments then they are a false prophet and should be stoned to death. We know that Jesus was not a false prophet.
Third, if Jesus had "declared all foods clean" then why didn't the unbelieving Jews who wanted to kill Him simply make that charge against Him? It would have been an open and shut case with the death penalty as the required punishment. Why did they try to trump up false charges against Him instead of using this? Because His contemporaries never thought He counseled rebellion against the commandments! If even His enemies did not believe He sinned in this way, why would we believe He did?
Fourth, if Jesus had "declared all foods clean" then he would have violated the commandment of not "adding to or taking away from" the Law (Deut 4:2, 12:32) which would be a sin. Had He sinned, He could never be the sinless redeemer of all humanity.
Fifth, if Jesus had "declared all foods clean" then He would not have only annulled the least of the commandments, He would have eliminated two entire chapters of the Bible! And yet He tells us, "Whoever then annuls one of the least of these commandments, and teaches others to do the same, shall be called least in the kingdom of heaven; but whoever keeps and teaches them, he shall be called great in the kingdom of heaven." (Matthew 5:19). We know for certain that Jesus will not be the least in the kingdom of heaven.
Sixth, if Jesus had "declared all foods clean" then His disciples were completely unaware of it. Peter was shocked by the vision in Acts 10 even suggesting that he eat anything unclean. And Paul, near the end of his life and his ministry, declared that he is, present tense, a Pharisee (Acts 23:6), who had "committed no offense... against the Law of the Jews" (Acts 25:8), and "done nothing against our people or the customs of our fathers" (Acts 28:17). The disciples' lives testify to the fact that Jesus never annulled the food laws.
Seventh, if Jesus had "declared all foods clean" then He would have been a hypocrite. Just a few sentences earlier in Mark 7, He berates the Pharisees telling them "You are experts at setting aside the commandment of God in order to keep your tradition." (Mark 7:9) How could He scold them if He was just about to turn around and do the same thing and set aside the commandments of God regarding food? He should have been agreeing with them instead!
Eighth, if Jesus "declared all foods clean" then why do the passages in Isaiah describing the era of Christ's thousand-year reign include a declaration that "those who eat swine's flesh, abominable things, and mice will come to an end altogether" (Isaiah 66:17)?
Because Jesus never declared all foods clean.
If you want to take a more detailed look at this passage, check out More Answers to Mark 7.
If you're curious about what Scripture actually says about food we recommend this article from Psalm11918.org entitled What Scripture Says About Food.