Catechesis consists of intentional, orderly instruction in the truths by which Christians are called to live - a sort of discipleship in 'mere Christianity'. The fact that catechesis has fallen out of the life and practice of many churches today is a major loss, leaving Christians undernourished and spiritually sluggish. Professor J. I. Packer responds that 'it is catechesis - vital ongoing teaching and discipling - that hits the bull's eye': it is of the utmost importance in developing a church that maintains orthodox beliefs. Packer urges Christians to know their faith so they can explain it to inquirers, sustain it against sceptics, and put it to work in evangelism, church fellowship, and the many forms of service aEURO this is the Christian's business of taking God seriously.