Were baptized into Christ (ebaptisqhmen ei Criston). First aorist passive indicative of baptizw. Better, "were baptized unto Christ or in Christ." The translation "into" makes Paul say that the union with Christ was brought to pass by means of baptism, which is not his idea, for Paul was not a sacramentarian. Ei is at bottom the same word as en. Baptism is the public proclamation of one's inward spiritual relation to Christ attained before the baptism. See on "Ga 3:27" where it is like putting on an outward garment or uniform. Into his death (ei ton qanaton autou). So here "unto his death," "in relation to his death," which relation Paul proceeds to explain by the symbolism of the ordinance.