The doctrine of Justification is called "the doctrine of a standing and falling church" for two reasons. First, it is an essential teaching that every true church must manifest. Second, it is a teaching that is perennially under attack, mostly due to the fear that it will remove the motivation for the pursuit of holiness. In this catechism sermon we focus on WHY the doctrine must be defended, and especially on the contemporary challenges from within the Reformed tradition, namely Norman Shepherd and the Federal Vision.