{Were baptized into Christ} (eis Christon ebaptisth(8874)e).
First aorist passive indicative of aptiz(935c). Better, "were
baptized unto Christ" in reference to Christ. {Did put on Christ}
(Christon enedusasthe). First aorist middle indicative of
endu(935c) (-n(935c)). As a badge or uniform of service like that of
the soldier. This verb is common in the sense of putting on
garments (literally and metaphorically as here). See further in
Paul ( Ro 13:14  Col 3:9f.  Eph 4:22-24  6:11,14 ). In  1Th 5:8 
Paul speaks of "putting on the breastplate of righteousness." He
does not here mean that one enters into Christ and so is saved by
means of baptism after the teaching of the mystery religions, but
just the opposite. We are justified by faith in Christ, not by
circumcision or by baptism. But baptism was the public profession
and pledge, the soldier's _sacramentum_, oath of fealty to
Christ, taking one's stand with Christ, the symbolic picture of
the change wrought by faith already ( Ro 6:4-6 ).