In her recent book on the temple origins of Christian worship (T&T Clark, 2007), Margaret Barker notes the various meanings attached to baptism in the NT. She disputes Paul Bradshaw’s conclusion that this variety means “the process of becoming a Christian was interpreted and expressed in a variety of ways,” arguing instead that there’s an underlying unity: “The little that can be recovered about the initiation of the ancient royal high priests suggests that this was the origin of Christian baptism.”

She even suggests that baptism “in the name” should be connected with the priestly vestments, which bore the name of the tribes of Israel and named the high priest as a holy one: “baptism ‘into/in the name of the Lord,’ meant marking as the high priest had been marked . . . . The person baptized became a high priest, or rather, part of the high priest, part of the Lord incarnate.”