From the earliest days of the Christian proclamation, the mystery of grace and the tragedy of sin stood at the center of the Church's preaching, worship, and self-understanding. The first believers did not approach these themes as abstract theological problems or philosophical puzzles. They encountered them as living realities woven into the fabric of their daily existence: the experience of human frailty, the awareness of moral failure, the longing for healing, the astonishment at divine mercy, and the transformative power of Christ's presence in the sacraments and in the life of the community. For them, grace was not a metaphor but a force that re-created the human person; sin was not merely a moral misstep but a rupture in the relationship between humanity and God. To explore how the early Christians understood these realities is to enter into the heart of the Church's faith, where the drama of salvation unfolds with clarity, urgency, and hope.