This document discusses the importance of purity in the church and among Christians. It argues that we must maintain pure doctrine, live pure lives, and practice pure love. Purity in these three areas is threatened by errors, worldliness, and selfishness, but Christians can guard purity by obeying God's word, dwelling on heaven, and properly loving God and others as Christ loved us. The summary concludes that if each Christian does their part to be personally pure, the church as a whole will also be pure.