The Lord says: "These people come near to me with their mouth and honor me with their lips, but their hearts are far from me. Their worship of me is made up only of rules taught by men.
Therefore once more I will astound these people with wonder upon wonder; the wisdom of the wise will perish, the intelligence of the intelligent will vanish."
Previously in this chapter Isaiah mentioned that the humiliation of the proud included their once proud speech being turned into mere mumbling."Brought low, you will speak from the ground; your speech will mumble out of the dust. Your voice will come ghostlike from the earth; out of the dust your speech will whisper." Is 29:4 So also their spirit is corrupted such that their intuitive understanding of the application of the scriptures is lost resulting in their worship turning into the mere legalism of manufactured rules and regulations. Their spiritual leaders may be likened to the religious leaders of Jesus' day who concerned themselves only with the letter but missing the spiirit and heart of the word. Indeed Jesus applies this very verse in Isaiah to them:
Mark 7:5-8So also from time to time and from place to place the Christian community has been guilty of the same. Therefore let us not esteem to highly the opinions of pastors, seminarians, and extra-Biblical theologians. But let us compare everything against the Bible itself. Be spiritually awake and alert in your thinking. He who has ears, let him hear.
The Pharisees and teachers of the law asked Jesus, "Why don’t your disciples live according to the tradition of the elders instead of eating their food with ‘unclean’ hands?" He replied, "Isaiah was right when he prophesied about you hypocrites; as it is written: "‘These people honor me with their lips, but their hearts are far from me. They worship me in vain; their teachings are but rules taught by men.’ You have let go of the commands of God and are holding on to the traditions of men."
The message of the cross is foolishness to those who are perishing, but to us who are being saved it is the power of God. For it is written: "I will destroy the wisdom of the wise; the intelligence of the intelligent I will frustrate." Where is the wise man? Where is the scholar? Where is the philosopher of this age? Has not God made foolish the wisdom of the world? For since in the wisdom of God the world through its wisdom did not know him, God was pleased through the foolishness of what was preached to save those who believe. 1Cor 1:18-21