Cornerstones is a discipleship tool for parents to use with their children and an approachable systematic theology book for parents. Ed: What is the basic premise of Cornerstones? Brian:Cornerstones is a pair of books—one for children and the other for parents—that covers the basic doctrines of the faith in a question-and-answer format, like a catechism. Years ago, when I was in seminary, I learned how the early church had used catechisms to train believers in the faith and I decided that I wanted to use this approach with my children. So I searched for one to use, but the ones…