God´s Word and prophetic action are appellants terms in Karl Barth Theology. The Theology as Church´s function, confess to God for the fact of speeking about God from himself. It thus makes it in the action of each christian individualy. This concept of theology presents the form through what Karl Barth comprehends the chrystian experience by means of the relation practice/theory/practice. This paper´s purpose is to cover the ways that Barth trod since his priesthood in Switzerland, his theological deepening after the First World War and the abendonment of his project of theology systematization. His work is unfinished, as unfinished is the theology produced by the Church. From this reorientation, He put the theology in the service of the Church. Affirms that it is the Church that teachs the theologian not the opposite. He nourishes himself of the church in order to conduct it against the most adverse circumstances. The theology must serve as edification to the Church, but it has also to conduct the Church to fully exert, as a dinamic community, its potentialities of service through the prophetic action that livens up the afflict and denounces the sin and the injustice.