Today Isaiah tells us, "Come, let us climb the Lord's mountain, to the house of the God of Jacob."
People of the ancient world believed that gods reside on high mountains and the higher the mountain, the more powerful the god who resides there.
Isaiah knew very well that Mount Zion was not the highest mountain. Yet he believed that God would establish it as the place from which the power of His word would go out to the whole world. This is the place where God will meet and speak with His people. This is where God will form His kingdom.