The present article wants to give an answer to the question about the reasons of God’s miracles and signs which we know from the Bible. In the Old Testament we find narratives of some miracles, for example about the exodus and the crossing of the Jordan, which tell us that through such deeds God revealed his greatness and might, so that people may become acquainted with Him and as a consequence, they may experience his goodness. The texts of the New Testament tell us about signs and miracles, for example about the sign of Jesus at Cana and about the Pentecostal event, which serve as a self-revelation of Jesus/God and his recognition by the people. The miracles and signs help to proclaim the Good News and to strengthen the faith of the disciples. In the biblical narratives God performs the miracles for the man, so that he has a participation in the fruits of God love.