5. The variation in construction after βαπτίζειν, first the dative ὕδατι without a preposition and then with ἐν, is probably due to the difference of sense between baptism with water and with the Spirit. But βαπτίζειν ἐν ὕδατι is found (Joh 1:31) where there is no contrast between sacramental and spiritual baptism.