Chapter 1 is an exposition of Heidelberg Catechism Lord’s Day 21, Q&A 54. The authors seek to understand from the Catechism what the relationship between the church and the world is in worship. Should the aim of the church be to make worship accessible to the world? Should worship be one occasion where the church displays her otherworldliness? Should worship be a means to attract the unchurched? Should worship be an expression of the church’s identity as aliens and strangers in the world? Specific attention is given to the holiness of the church in answering these questions.