em>A Kingdom Within presents the conversion of King David as a paradigm of conversion and identifies and examines a number of essential truths about man's sin and God's mercy. First and foremost, it shows that King David's experience of God's mercy and the definitive revelation of that mercy in the mission of Jesus Christ, especially His paschal mystery, shed light on one another. The guiding principle of this work, then, is the teaching of Vatican II: "God, the inspirer and author of both Testaments, wisely arranged that the New Testament be hidden in the Old and the Old be made manifest in the New. For ... the books of the Old Testament with all their parts, caught up into the proclamation of the Gospel, acquire and show forth their full meaning in the New Testament (see Mt 5:17; Lk 24:27; Rom 16:25-26; 2 Cor 14:16) and in turn shed light on it and explain it" (Dei Verbum, 16). Presuming the faith and working of grace in readers, the hoped-for fruit is a renewed confidence in God's mercy. God's mercy is His greatest attribute in relation to us. It is the truth that sets us free to face our sins, to turn to God for forgiveness, and through this conversion to give glory to God. For, the glory of God is the manifestation of His holiness, and nothing manifests His holiness more than the new life of sinners who have been forgiven and reconciled to God. Conversion, then, is the first step into deeper communion with God in holiness and charity. This, in turn, becomes communion in mission for the sake of leading others to experience God's mercy. This, too, is His glory. The biblical witness to King David's conversion teaches us that conversion, holiness, and mission are inseparable. Conversion flows into holiness and mission flows from it. The hope that drove the writing of this book is that renewed contact with the divinely inspired witness to King David's conversion might contribute in its own modest way to the realization of Vatican II's call to holiness through conversion, and in this way bear the fruit of reinvigoration of the Church's mission to proclaim the Good News of God's mercy and the fulfillment of His plan for mankind.