What does Isaiah 1:11 mean?

The Lord continues to make His complaint against the people of Israel in Judah. It becomes clear the problem was not they were not "religious" enough. They were practicing the ritual offerings required under the sacrificial system in the law of Moses. Because of the sinful condition of their hearts, however, the Lord no longer wants these sacrifices from them. God questions the point of their sacrifices. In Isaiah 1:13, He calls them "vain offerings."

To be clear, the law required Israel to offer these things to God. They were meant to atone for their sin as well as to express thanks and praise to the Lord. The problem was that the people assumed that practicing these religious rituals would mask their true heart. They worshiped the one, true God of Israel as the pagans worshiped their false gods, offering meals and other food in exchange for blessings and protection while continuing to live in their sin.

When practiced by God's people, religious rituals are not in and of themselves worthless. They become worthless when they no longer represent the true heart feelings and attitudes of those who practice them. These practices are symbolic, and they become meaningless when they no longer symbolize the inner lives of God's children.