Paul allowed pagans to become members of the newly founded communities of Christ-believers and thus members of God’s covenant people, Israel, without becoming circumcised. However, even if many of the ‘pagan Christians’ who became members of the new messianic movement had a background as God-Fearers in the frame of diaspora synagogues, the radicalism of their ‘step in faith’ can hardly be overestimated. With their turn from different pagan cults and their gods to the mysterious God of Israel and his crucified and risen Son, Jesus Christ, a whole coordinate system of human relationships, expectations, hopes and norms must have changed. This paper explores the construction of Christian identity and its relationship with ethics according to Paul. It is illustrated how Paul himself describes the system of changed relationships: turning away from the idols towards the living God, being in Christ or – together with others – part of the ‘body of Christ’. Moreover, these three dimensions of new relations – to God, to Christ and to the fellow believers in Christ – correspond to three reference points for ethical decisions in Pauline communities: the command to love one another, the idea of human conscience (as a voice coming from God) and the idea of the ‘ethos of Christ’.