The article explains the fundamental features of the Lutheran two kingdoms doctrine and the Reformed doctrine of the Lordship of Christ and finds strong convergences of both in addressing political realities without leaving the Gospel perspective aside. Since Catholic concepts show a similar profile, an ecumenical public theology emerges. Six guidelines for a public church are presented to describe the consequences of a public theological approach to politics for the churches. Authentic faith witness is as much part of these guidelines as 'bilinguality', that is, the capability to talk the language of secular discourse and prophetic speech, which is put in relationship to the necessity of concrete daily political processes. Thus, in the end the article explains the profile of public theology in relation to liberation theology and political theology. The article explains the fundamental features of the Lutheran two kingdoms doctrine and the Reformed doctrine of the Lordship of Christ and finds strong convergences of both in addressing political realities without leaving the Gospel perspective aside. Since Catholic concepts show a similar profile, an ecumenical public theology emerges. Six guidelines for a public church are presented to describe the consequences of a public theological approach to politics for the churches. Authentic faith witness is as much part of these guidelines as 'bilinguality', that is, the capability to talk the language of secular discourse and prophetic speech, which is put in relationship to the necessity of concrete daily political processes. Thus, in the end the article explains the profile of public theology in relation to liberation theology and political theology.