We know from previous biblical books of history that King Ahaz was likely the most wicked king to reign in Judah. God still tried to reach him, He offered Ahaz a sign, but Ahaz faked humility and refused it. So God chose His own sign - the birth of Jesus Christ.
In this dark time, Isaiah's sons' names were significant. Shear-Jashub means "a remnant shall return" which is both a name of judgment (the nation will be destroyed with only a remnant remaining) and mercy (there will be a remnant, and they will return). Maher-Shalel-Hash-Baz meant the Assyrians should "hurry to the spoils" - judgment.
Into this darkness the prophecy of Immanuel came. God with us. Our dark world desperately needs the Light and yet the wicked love the darkness rather than the light because their works are evil (John 3). They don't even realize that they're rejecting their only hope.
Indeed, Isaiah tells us to wait for the Lord, to put our hope in Him.
In Mark we see the Light in action - demonstrating His authority over demons and sickness. We also see Him pointing out the Pharisees legalism, and reminding them that the law required love.
Love God and love our neighbour. It's as simple, and as difficult, as that.
Tomorrow's Bible In a Year Passage passage: Isaiah 9-10, Mark 3:20-35