“Catechesis” comes from the Greek word, katekhesis, meaning “instruction by word of mouth.” Broadly speaking, then, catechesis may refer to any number of disciplines that are taught orally. However, “catechesis” has come to denote, specifically, Christian instruction.
We could summarize catechesis, then, as follows: Catechesis is basic Christian education.
What Is Christianity
In order to see why Jesus Christ must be the center of catechesis we must begin by asking the question, “What is Christianity?” If it is simply a moral code, then that code ought to be at the heart of catechesis. If Christianity is false, then its falsity ought to be the heart of whatever is taught about it.
But whatever else Christianity may entail (Church services; moral teaching; bingo, etc.) to the Christian it is first and foremost a person. “Christianity,” said St. John Paul the great, “is not just a book of culture or an ideology, nor is it merely a system of values or principles, however lofty they may be. Christianity is a person, a presence, a face: Jesus, who gives meaning and fullness to human life.” 
According to St. Paul, Everything – Jesus = Refuse, and Nothing + Jesus = Everything.
“I count everything as loss because of the surpassing worth of knowing Christ Jesus my Lord. For his sake I have suffered the loss of all things, and count them as refuse, in order that I may gain Christ,” (Phil. 3:8)
It follows, therefore, that the person of Jesus of Nazareth must be the heart of Catechesis. It is Christ, says Ratzinger and Shonborn, “who is the overwhelming light that illuminates the whole exposition of faith.”  “The heart of the Deposit of Faith, its center, lies in the revelation of the Heart of God in the Person of Jesus Christ” 
My argument could be summarized thusly:
Premise 1: Catechesis is basic Christian education.
Premise 2: Christianity is, first and foremost, the person of Jesus of Jesus of Nazareth.
Conclusion: Therefore “[a]t the heart of catechesis we find, in essence, a Person, the Person of Jesus of Nazareth, the only Son from the Father. (CCC 426).
1. “Switzerland John Paul II,” http://www.traces-cl.com/july04/arisechrist.html (10 October 2010).
2. Joseph Cardinal Ratzinger, Christoph Schonborn. Introduction to the Catechism of the Catholic Church. (San Francisco. Ignatius Press. 1994). 45
3. Petroc Willey, Pierre de Cointet, and Barbara Morgan, The Catechism of the Church and the Craft of Catechesis (San Francisco, CA: Ignatius Press, 2008), xiv.