In NTS 62.3 (July 2016) David Horrell argued that certain passages in 1 Corinthians 7 and 1 Peter 3 showed ‘ethnicising’ traits among the early Christians. He set this result against an alleged trend in scholarship that would distinguish and disparage a closed ethnic Judaism in relation to a new spiritual-universal Christianity. The present authors’ work was proffered as representative of this trend, even though no evidence was cited for such a connection and their work moves in a very different direction. Leaving aside Horrell's interpretation of the New Testament passages for reasons of space, this article takes up the larger question of Judaean and Christ-movement identities by reconsidering the position of Ioudaioi and Christ-followers in the early Roman Empire. Using different but convergent (social-scientific and historical-philological) methods, we find that ethnos-language was everywhere applied to the Judaeans, that this reflected normalcy and exchange with the world, and that Judaeans thus met the criteria of an ethnic group. Early Christians had no such recognised place. Their voluntary associations largely rejected ethnos- and polis-commitment or identity. Neither Judaean openness to the world nor Christian alienation supports the position that Horrell attributes to us.