Defiled food may hurt our bodies, but it cannot reach our spirits (John 3:6).
The scribes and Pharisees missed the principle of spiritual purity taught by the Old Testament ordinances and became obsessed with strict adherence to their rituals. While they enforced the laws dealing with the physical realm, they had become completely corrupt in the spiritual realm.
"The law is not of faith." When put together with Romans 14:23, "...whatsoever is not of faith is sin," this statement must have been near blasphemy to the legalistic Jews, just as it is to legalistic Christians. It is sin for the New Testament believer to try to relate to God by trying to keep the Old Testament law. The law itself is not sin (Romans 7:7). But it is sin to try to use the law for justification with God. This was never the purpose of the law.
Under the law a person got what he deserved. Under faith, the New Testament believer receives grace because of what Jesus did for him. Anything other than faith, especially going back to the Old Testament law, wipes out the work of Christ (Galatians 2:21) and is the worst sin of all. Only faith in Jesus Christ gets rid of guilt and condemnation. With a great price Jesus has purchased our freedom. We must walk in it and enjoy His Life.