Billy Marsh became a Christian at an early age, and soon thereafter, he discerned that the Lord was cultivating a desire for vocational Christian ministry. While in college, Marsh developed a passion for the recovery of the pastor-theologian role. For Marsh, this role represents the inherently pastoral nature of the knowledge of God of which theology that is done in accord with the Scriptures seeks to understand. His research interests have been specifically located within the fields of Biblical Theology, the Doctrine of Scripture, Hermeneutics/Biblical Interpretation, Christology, Reformation Studies, and Martin Luther.