And they were strange. There is no good evidence for vicarious baptism anywhere in the New Testament or among the earliest apostolic fathers. We really do not know. If it were something like that, one could understand why Paul does not make a federal case of it. In any case, Paul's clear emphasis is that people are justified by grace through faith , which demands a personal response.
Christian baptism is part of that personal response, even as it is a convenantal pledge.
By D. A. Carson, research professor of New Testament at Trinity Evangelical Divinity School, Deerfield, Illinois.