"'Who is it he is trying to teach? To whom is he explaining his message? To children weaned from their milk, to those just taken from the breast? For it is: Do this, do that, a rule for this, a rule for that; a little here, a little there.'" NIV translation
We see the reaction of the religious leaders to Isaiah's call for them to stop the things they were doing.
They mocked him by comparing his call to repentance with that of a mother putting down rules for her child. In their arrogance, the leaders did not feel like they had to answer to any man for their actions and they were not afraid of offending God.
This section of the chapter can be a little bit confusing but, if you remember that Isaiah is talking about sanctification and not salvation, you can better understand it.
He is talking to people that are supposed to be serving God but they are acting like those that do not care about God. The Apostle Paul faced a similar situation with the Roman believers and, like Isaiah, he called for the people to be holy because they are saved (see Romans 6:15).
We must also remember that the people of Isaiah's day did not have access to God's grace for salvation because the Messiah had not come.
So, what does this have to do with us in our world today? This allows us to see that, when faced with the Law and our inability to keep it, we have two options. The first option is to cry out for God's mercy and accept His grace through Jesus Christ which will lead to freedom from the Law of sin and death. The second option is to turn away from all attempts to keep the Law and just do whatever you want without regard for the consequences.
For those of us who are in Christ, Isaiah's call to the religious leaders is a reminder to us that we should be a good witness of the power of Jesus Christ. The lost and those who are still learning to understand the relationship between grace and their faith are watching us. We willingly limit our personal freedom in Christ for the sake of others.