This book delves into the theological and historical aspects of early Christianity, focusing on its connections with Jewish apocalypticism and the reinterpretation of key Jewish concepts and ideas in light of the life, death, and resurrection of Jesus. The text explores the influence of Jewish thought, particularly the Qumran community's understanding of messianism, prophecy, the Kingdom of God, and the Holy Spirit, and how these ideas were transformed in early Christian teachings. Beginning with an introduction to the historical context and the world of Jewish apocalypticism, the book investigates the key theological themes that emerged in early Christianity. It provides an in-depth examination of the figure of Jesus, focusing on his reinterpretation of Jewish messianic expectations, the role of the crucifixion and resurrection in inaugurating the new creation, and the establishment of the Kingdom of God. Key moments such as the coming of the Holy Spirit at Pentecost are shown to mark a transformative shift, as the Church became the living, active presence of Christ in the world, empowered by the Spirit to continue his work. The book explores the concept of the Church as the Body of Christ, emphasizing its role as the new covenant community and the fulfillment of God's promises to Israel. It also examines how early Christianity understood the role of the Holy Spirit in believers' lives, transforming them into the image of Christ and empowering them for mission. Through these theological shifts, the early Christian community redefined salvation, ethics, and the nature of God's Kingdom. In conclusion, the book offers a comprehensive exploration of how early Christianity both built upon and radically transformed Jewish apocalyptic ideas. It sheds light on how the resurrection of Jesus became the defining event of Christian faith, marking the beginning of a new age in which God's Kingdom is both a present reality and a future hope. The work reflects on how these theological changes helped shape the identity of the Church, its mission, and its understanding of salvation, establishing the foundations of Christian doctrine that would influence generations to come.