Those who have been caught in an armed conflict would certainly know what fear and danger is.
More so when they are are surrounded by the enemy who is waiting to break through their defences. They will be at the mercy of the enemy and there may be no mercy at all.
They would certainly know what it means when the 1st reading says that "the heart of the king and the hearts of the people shuddered as the trees of the forest shudder in front of the wind".
If we were king Ahaz, and being surrounded by these enemies and knowing that they will make us suffer when they break through our defences, we would certainly look for help from someone more powerful who would also be able to disperse these enemies.
King Ahaz had that option of Assyria, the superpower at that time. But the prophet Isaiah gave him another option, and that is to turn to the Lord for help.
But in these dire circumstances, we would certainly prefer the security of a power we could see and feel, to believing in the word of an invisible God spoken by a humble prophet.
And as the Lord said, after giving all the assurances, "But if you do not stand by me, you will not stand at all." Still in the end, king Ahaz chose an earthly power, and eventually he also didn't stand at all.
Neither did the towns of Chorazin and Bethsaida that were reproached by Jesus, because despite the miracles that He worked there, they did not repent.
Let us repent and renew our faith in God and trust that He will save us from fear and danger. More so if we had seen the marvels of the Lord, then if we still do not stand by Him, then we will not stand at all.