You could write about Old Testament passages that talk about Jesus. Like these:

(Psalms 72:1-8 NIV) Of Solomon. Endow the king with your justice, O God, the royal son with your righteousness. {2} He will judge your people in righteousness, your afflicted ones with justice. {3} The mountains will bring prosperity to the people, the hills the fruit of righteousness. {4} He will defend the afflicted among the people and save the children of the needy; he will crush the oppressor. {5} He will endure as long as the sun, as long as the moon, through all generations. {6} He will be like rain falling on a mown field, like showers watering the earth. {7} In his days the righteous will flourish; prosperity will abound till the moon is no more. {8} He will rule from sea to sea and from the River to the ends of the earth.

(Zechariah 12:9-10 NIV) On that day I will set out to destroy all the nations that attack Jerusalem. {10} "And I will pour out on the house of David and the inhabitants of Jerusalem a spirit of grace and supplication. They will look on me, the one they have pierced, and they will mourn for him as one mourns for an only child, and grieve bitterly for him as one grieves for a firstborn son.