I notice that other than abu_hurriya, who (in another thread) is considering becoming a Muslim, that I am the only Christian who has responded here. I would ask then that you might grant me a little leeway in being selective in my responses. I have not the time to respond to everything, there are some concepts that I might not be as conversant on as others, and there are some that I simply may not think as essential as others as well. So, if I miss something that is truly important to you, please bring it to my attention a second time, but also know that I simply am not going to write an entire systematic theology in this space, which, whether you realize it or not, is what is being called for to adequately deal with the depth of the questions here.
Lastly, others speaking from what I suppose is their knowledge of what they believe Christians believe, but have expressed things foreign to my actual belefs. I don't know that it is worth going back to correct such statements, but I do caution those who read responses from those who are not Christians that they may or may not have understood and properly shared the beliefs of actual Christians.
Before I answer much about baptism, as I have expressed above, there are some differing understandings with regard to baptism among Christian groups. Thus, for those who pay attention to such things, it is worth noting that I am a United Methodist pastor. The United Methodist Church is generally classified as a mainline protestant denomination. Its roots go back to the Anglican Church (i.e. Church of England) from which it separated, not over theology but as a consequence of the American Revolution. Until recently the United Methodist Church was the largest protestant denomination in the United States with about 8 million members, plus another 4 million scattered around the world; the largest protestant denomination is now the Southern Baptist Convention.
OK. That's enough of an introduction. Now to baptism:
To be honest, through the history of my own denomination, baptism has been viewed in diverse and even contradictory ways.
For instnace: John Wesley -- an Anglican priest who was the spiritual forefather of Methodism -- retained the sacramental theology which he received from his Anglican heritage. He taught that in baptism a child was cleansed of the guilt of original sin, initiated into the covenant with God, admitted into the Church, made an heir of the divine kingdom, and spiritually born anew. While baptism was neither essential to nor sufficient for salvation, it was nonetheles the "ordinary means" that God had designated for applying the benefits of the work of Christ in human lives.
On the other hand, although Wesley affirmed the regenerating grace of infant baptism (I hope that is not to technical a term; it basically means that God gives new spiritual life in baptism because original sin has spiritually killed everyone), he also insisted on the necessity of adult converstion for those who had fallen from grace. It should be obvious that this means Wesley is trying to have his cake and eat it too. How he handled that was to say that a person who matures into moral accountablity must respond to God's grace in repentance and faith. Without personal decision and commitment to Christ, the baptismal gift is rendered ineffective.
Now, as to Woodrow's question, what role then does the cross have to play? It is Christ's work on the cross that baptism initiates one into. The whole concept of baptism is that by it we are spiritually joined with Christ being baptized into his death and subsequently raised with him into new life.
Romans 6
3Or don't you know that all of us who were baptized into Christ Jesus were baptized into his death? 4We were therefore buried with him through baptism into death in order that, just as Christ was raised from the dead through the glory of the Father, we too may live a new life. 5If we have been united with him like this in his death, we will certainly also be united with him in his resurrection.
True baptism is not something practiced only by Christians; there are other non-Christians groups that baptized for their various reasons. For that matter, circumcision is not something practiced only by Jews. But we do understand that it is a symbol to the Jews of the covenant relationship that they understand they have with God. So, too, baptism serves a similiar function for Christians:
Colossians 2
11In him you were also circumcised, in the putting off of the sinful nature, not with a circumcision done by the hands of men but with the circumcision done by Christ, 12having been buried with him in baptism and raised with him through your faith in the power of God, who raised him from the dead. 13When you were dead in your sins and in the uncircumcision of your sinful nature, God made you alive with Christ. He forgave us all our sins, 14having canceled the written code, with its regulations, that was against us and that stood opposed to us; he took it away, nailing it to the cross.
You will note in that passage the connection between baptism and Jesus' death and resurrection that I spoke of above. It is as if by the sacrament of baptism, God gives us new life in the same way that Jesus' dead body was given new life by the power of God. And the concept of circumcision is also attached to baptism, that it is an initiation into a new covenant community, a new family, that in being joined with Christ in baptism we all become children of God, and can look forward to our own resurrection:
Romans 8
16The Spirit himself testifies with our spirit that we are God's children. 17Now if we are children, then we are heirs—heirs of God and co-heirs with Christ, if indeed we share in his sufferings in order that we may also share in his glory.
I'm sure that's enough to answer maybe one question, and raise 20 more. So, I'll stop here for the moment, and see if I'm tracking well with those who are interested in this thread, or if I need to be addressing other issues entirely.
original sin is releted to food