In 1646, the Parliament of England called for an Assembly of Pastors to gather together and agree upon the basic tenets of the Christian Religion. They drew up a document called the Westminster Confession of Faith. In addition, they included the Larger and Shorter Catechisms, which are dialogues that teach the breadth of Christian Theology. The Larger Catechism was meant for men who would shepherd congregations, and lead their families in Christian Doctrine. The Shorter Catechism was originally designed for women and children.
The Shorter Catechism has become a standard element in testing for pastoral ordination. Many families still catechize their children, and there is an increasing trend toward reviving this practice within the Presbyterian PCA, OPC, and other Reformed denominations.
In short, Holly desired to learn the Shorter Catechism herself, and found that she came by creating melodies to the texts with relative ease. She also saw it as a challenge to complete all 107 songs. As she began working with kids at church with the songs, she saw that it made learning the questions simple and fun.
She has since been contacted by numerous people throughout the world, who have expressed interest in making the WSC Songs widely available. Not only is the project great for committing biblical theology to memory, but it is conducive to use with personal devotions.