For more than two millennia believers have struggled with the antinomy of God's absolute sovereignty over and man's ultimate responsibility in justification and sanctification. Theologians have used some version of the terms "active justification" and "definitive sanctification" in an attempt to illuminate this mystery. However, in the past decade scholars have begun to criticize these concepts, saying that they are unsupported in Scripture, lead to theological confusion, and are of no practical benefit to believers. Through the work of theologians from the broader Dutch Reformed tradition, especially Herman Bavinck, Alexander Comrie, Herman Witsius, and Abraham Kuyper. Jae-Eun Park demonstrates that the terms "active justification" and "definitive sanctification" are derived from Scripture and serve to clarify, not obscure the doctrines of justification and sanctification. In addition, the book shows that neglect, misuse, or misunderstanding of the terms have resulted in contemporary criticisms that are unconvincing and unfounded. Writings of the aforementioned theologians define and expound four characteristics held in common between active justification and definitive sanctification, i.e., inseparability, objectivity and decisiveness, Christ-centeredness, and God's absolute sovereignty -- concepts of the mentioned theologians. All four characteristics of active justification and definitive sanctification emphasize the "God-driven" nature of salvation. Jae-Eun Park explains how -- when properly defined and presented -- the two terms are important theologically, bringing clarity to the issue of the perfect balance between God's sovereignty and human responsibility in salvation. She also shows how active justification and definitive sanctification offers practical assurance of their perseverance unto glory to true believers, and provides pastors with an invaluable tool for exhorting parishioners who may have lapsed into either triumphalism or defeatism.