The process of secularising and relativising modern human life affects believers in their experience. At the same time, there is an interest in spirituality, but often of an individualised and non-extremous nature. It is therefore necessary to reflect on the correct understanding of the Church’s identity and mission. The relevant concept for describing this identity is communio. The article clarifies the correct understanding of it in the bibliological key due to the ambiguity that appears in the theology publications as well as in non-theological sciences. It is of particular importance on the basis of spiritual theology, defining the nature of unity between Bog and humans. The analysis of the Star Testament reveals important aspects of the EU from the Alliance. However, an analysis of the New Test shows that Chrystus has been fully united in Jeuss Chrystus and continues in the Church. For this reason, Christian spirituality must be interpersonal, christocentric, chrystoform and ecclesiastical. This process shapes moral life, which is reflected in individual, social, economic and even political life.