What is the theme in Catechism of the Catholic Church by Catholic Church?

One of the themes of this book is to provide a concise overview of the Roman Catholic religion. It is done so that the most important aspects of the faith can be understood and shared.

This information is set out so that any reader can better understand the religion. The methods of the Church are designed to enhance the fulfillment of its purpose which is to unite God with man such that all mankind will be saved first from sin and ultimately from death and the limitations of earthly existence.