This book contains a methodological fundamental-dogmatic study, which frames a comprehensive overview of the Church in the light of reason and faith. The understanding of the Church in the history of Christianity was – and still is – a subject of numerous misunderstandings, either among the believers themselves or those who observe it from the outside. Presenting the post-conciliar approach of the integral ecclesiology, the author puts a stronger emphasis on biblical origins and nature of the Church and on the split between the synagogue and the young community of followers of Jesus Christ. He expands the hallmarks of the Church from the usual four to five (Marianity) and displays a growing communio in practice and in ecclesial self-awareness.