Lots of interesting stuff here including so evidence that Christ and his followers referred to the old Testament word in the Septuagint, not the Hebrew. This verse with the previous one, quote Isaiah 29:13. The KJV translation of this verse is misleading, with the KJV translation of the old Testament Hebrew coming closer to the meaning of the Greek here. In the original Hebrew, this line is translated in KJV as saying, that "the fear of God comes from the teaching of men, not from God." The Greek could be translated similarly. Christ is actually telling people that they have nothing to fear from God, that the fear of God is taught to enforce the orders of men.

The sense of this verse and the previous one (Matthew 15:8) is to say that people think mentally they love God, but they have no feeling for God or relationship with Him. They falsely feel fear God because they teach the thoughts and preconceptions of men.

Interestingly, there is a real difference between the English translation of the Greek and the original Hebrew that doesn't exist between the Hebrew and the Greek. The English, at least of the King James, clearly did not look at the Hebrew version when creating a translation.