It's hard to fully grasp the concept of the "fear of The Lord" in quite the way that is being explained in this passage. Ancient Israel was caught in idolatry and in the pressures of mounting imminent military threat from Assyria. As such the people readily turned to all sorts of false gods in the hopes of stability and staving off invasion. But God comforted Isaiah with this warning to stay faithful.
The only hope for God's people was found in Him. Had they honored Him as holy, kept on obeying His law, and truly feared Him, the promises of protection could have spared them. But they would not return to God. They kept falling into the patterns of idolatry that they saw around them. They caved to social, political, and personal pressures. The tragedy that resulted from this was that Assyria ransacked Israel and those northern ten tribes never recovered. They are lost to history.
Learning from Israel, I admit that my own heart definitely feels the pressure to cave. That sort of thing never really goes away. It is a steady gravity-like pull. In my case it is not overt idol worship, but it is a form of unfaithfulness to cave to the pressures around me. And it will not be easy to stand Christian in a pagan land. I believe it is wrong to stand only as an act of defiance. Instead, I believe that to stand means that I bow only to The Lord of heaven. I only fear losing Jesus. My life means nothing else than Him.