Since the Second Vatican Council, the question of dialogue between Christianity and Islam has taken a special development. The Church tried to get to know Islam in various ways. One of the questions arising from the output of the dialogue is as follows – are we talking about the same God or another? The article considers this issue. First, it is discussed the meaning of God’s name in the Bible, especially in the Old Testament. Then the topic of meaning of God’s name in Islam was taken up. It is complemented by the Christian message about Jesus Christ. It is in him that God makes his name definitively complete. Therefore, it should be emphasized that the interpretation of God’s nam eis different in Christianity and Islam.