Public Theology analyses the role of religion in society and deduces ethical positions from religious traditions. An instrument for this, the translation into secular discourse, has already been criticised. Therefore it is necessary to reflect whether Public Theology is already ethically active by describing its present. Public Theology then wouldn't be a reaction to a described reality but rather have an experimental effect by describing reality - like a laboratory with its interdependence of description and action. This is shown by reflecting two theological strategies in Bonhoeffer's thoughts, by reflecting on metaphysics and secularity, by criticising the concept of the public, by shifting the understanding of Christology and widening the meaning of theological ethics.