When God shows up in the Bible, people are generally terrified and fall on the floor, afraid for their lives. Isaiah reminds the people (and us) that there is going to be a day when that happens to all of us. He tells us three times that we will be on our faces when God shows up in his glory (v10,19,21). Everything that we trust in, every idol that we cling on to will be shown up for what it really is. For the nations at that time that was things like the cedars of lebanon and the ships of tarshish that brought wealth and power. Or the towers and fortified walls that made them fell safe and secure. For us it's the security of the well-paid job. Or the status of the area we live in. On that day, Isaiah tells us, everything that seems big, important and powerful now will be brought low. Only God will be exalted on that day.
When faced with God, people will cast away their idols (v20). So what is the solution to our idolatry? Look at God, not man
Stop trusting in mere humans,
who have but a breath in their nostrils.
Why hold them in esteem?