If someone asked you to define "resurrection" what would you say? Why is resurrection central to Christianity? I would submit that many would struggle with how to respond to such questions, particuarly in light of our modern beliefs. It seems many modern understandings of resurrection and after-life death sound more like they are from Plato than they are from the New Testament. (i.e. the body is bad and the soul is good, and at death the body and soul are separated forever, the soul going to heaven and the body decaying to nothing.)
A helpul resource I have found in better understanding resurrection is NT Wright's book, Surprised By Hope: Rethinking Heaven, the Resurrection, and the Mission of the Church.
Wright walks the reader through 1st century Jewish and pagan understandings of resurrection to clarify an orthodox Christian perspective on what resurrection is. He then looks at the implications of such an understanding for the future, exploring what heaven is and how we are to understand it (i.e. not just life after death, but life after 'life after death'.) Then in the third part of the book, Wright spells out the implications of resurrection on the mission of the church.
I am only part way through this book, but I have found Wright's book very helpful in articlulating a core component of the Christian faith. I am so thankful for theologians/pastors like Wright and his ability to help clarify the Christian faith and how it is embodied in our everyday lives.