Talking about baptism has a tendency to start fights among Christians, but I gave in to the urge to offer a key metaphor for me in a post on another blog so I thought I'd let folks here have a look too.
"Maybe the significance of baptism isn't in what it "does to" the baptized, but in what it "does to God." Perhaps baptism is a way God has empowered us to "bind God" to the person being baptized in a way that has eternal, spiritual significance.
For a metaphor, consider this. I traveled to Vietnam years ago, empowered by my wife to legally bind her (and me) to a child through my own signature on her behalf. Signing my name is a routine and frequently meaningless act, but in this context, it had huge, real and lasting significance for me, my wife and the child. (Her name is Amy.) In the same way, washing with water is usually not very meaningful, but in the context of baptism that act could have real significance.
The metaphor could be extended to address some of the other struggles around baptism. Suppose my wife and I had made a personal commitment to provide in every way possible for the welfare of the child *regardless of whether the formal adoption was allowed to go through.* Our ability to deliver everything our hearts desired to Amy might have been hindered if the formalities couldn't be enacted... (it wold have been pretty hard to get her out of the country and situated with American citizenship, for example!) Who knows, maybe we would have ended up finding it necessary to "move into the neighborhood" (See John 1:14 the Message) and become citizens of Vietnam in order to follow our hearts and care for the child we had *unilaterally* claimed as our own. When you use this metaphor as a lens, you can see nicely that the underlying commitment is the real thing, the main thing, but it's also helpful to have the formalities enacted since that 1) makes the commitment public to all and 2) makes it much easier for the blessings of the relationship to flow to the child."