What is it about Isaiah's prophecies that are so powerful? Most of his prophecies focus on Jesus Christ, especially Jesus as our Messiah and Redeemer. On the Atonement - the Savior's propitiation for our sins - Isaiah wrote, "He is despised and rejected of men; a man of sorrows, and acquainted with grief: and we hid as it were our faces from him; he was despised, and we esteemed him not. Surely he hath borne our griefs, and carried our sorrows: ye we did esteem him stricken, smitten of God, and afflicted. Be he was wounded for our transgressions, he was bruised for our iniquities: the chastisement of our peace was upon him; and with his stripes we are healed. All we like sheep have gone astray; we have turned every one to his own way; and the Lord hath laid on him the iniquity of us all. He was oppressed, and he was afflicted, yet he opened not his mouth: he is brought as a lamb to the slaughter, and as a sheep before her shearers is dumb, so he openeth not his mouth" (Isaiah 53:3-7). How much clearer could Isaiah be about Jesus' role as Redeemer and as our Savior?
Isaiah also wrote much about the temple and temple-related doctrines. "And it shall come to pass in the last days, that the mountain of the Lord's house shall be established in the top of the mountains, and shall be exalted above the hills; and all nations shall flow unto it. And many people shall go and say, Come ye, and let us go up to the mountain of the Lord, to the house of the God of Jacob; and he will teach us of his ways, and we will walk in his paths" (Isaiah 2:2-3). Isaiah wanted the people and all of us to know that the Savior, living pure, and the temple should be central in our lives. The Savior's Atonement should be particularly central. Those are some of the "best" things we should focus on.
Link to part 4 of of this essay.