The Catechism in Questions & Answers

25. What is meant by the expression: “Jesus Christ is the centre of the Scripture?”

The central element of Holy Scripture is Jesus Christ. That is what is brought to expression with the words: “Jesus Christ is the centre of the Scripture”. It is for this reason that even the Old Testament must be interpreted on the basis of Him. The Old Testament prophesies, and prepares the way for, the arrival of the Messiah. The New Testament relates of Jesus’ activity in the present and the future.

Messiah: see Question 112.