The theme of Christian testimony is the main focus of this work. According to Salvador Pié-Ninot on his Fundamental Theology, testimony is presented as the new empirical way. It means a new way in which the daily life of the Church with its various experiences, sometimes even paradoxical ones, presents itself as a coherent and plausible reason to believe. After all, testimony is a first condition required to the credibility of the faith. It is important in the apologetic-dialogical task of Fundamental Theology. Within this, in the part of Fundamental Ecclesiology, testimony is considered as a key element of Church s credibility. It is known as via testimonii, because it is the most emphatic, notorious and coherent way for evangelization. In the perspective of testimony, according to Pié-Ninot, testimony is always theological; it is an ecclesial testimony like a mystery wrapped in paradox. Thus, Christian s testimony drives us to an apologetic task, making Church s dialogue easy. It can be personal dialogue (through prayer to God and in the Liturgy) or with the brothers (in an Ecumenical Dialogue or an Interreligious one). It can also be in a perspective of diakonia in the service of love to our brothers.