Thank you for your response.
My issue is with the word necessary. It's been brought up in this thread that you can't know the fate of unbaptized stillborn children or infants. However, AC IX specifically addresses this issue and condemns as an Anabaptist heresy that children can be saved without Baptism. As to adults, I would point out the with Philip the Deacon, he seemed to not have a problem with Baptism right away, neither did Paul in Acts 19.
I know that Mark 16:16 says unbelief damns (getting beyond the issue that Mk 16:16 is not part of the original text), but it shows that faith and baptism (which are profoundly interconnected) saves. I'm saying, just in terms of logic, that you can't infer that that means lack of Baptism doesn't damn. True faith in Christ is always accompanied by Christian Baptism, there's no reason to really delay this and the Bible knows of no such practice, that's one of the reasons Confirmation developed in the early church, so that a man who had been baptized could make confession of Christ and Him crucified for himself.
I doubly agree with you about the thief on the cross. That's why when people try to bring him up as an example of Baptism not being necessary, it's invalid. It's just like arguing that Daniel or Jeremiah wasn't baptized, well, duh, Christian baptism wasn't instituted yet.
My argument is simply that: "Baptism is necessary for salvation." And "necessary" means "necessary." There's been a dangerous trend not just in the Lutheran church but in other churches that teach the Biblical doctrine of Baptismal regeneration. The RCC, to given an example, has even systematized it into something called "Baptism of desire" after Vatican II, people that would want baptism already have it. That's why most RCC bishops and even the pope make these completely heretical statements that non-Christians and unbaptized people can be saved. Now, if the Baptists are right, and Baptism is just a token, or a symbol, or a representation of faith already given to a man, then sure, Baptism isn't necessary for salvation. But if Baptism actually does something, and the Scriptures make it obvious that it does, then it has to be necessary for salvation. It's not optional. It's why I have no problem telling someone that isn't Baptized, "No, you're not a Christian." There's really no middle ground here, either it's necessary or it's not.
"Necessary for salvation" means "necessary for salvation." Just like when I tell the reformed "is" means "is" or when I mention to my RCC friends "not by works" means "not by works." I'm a simple man, I let the words of the Bible and the Confessions mean what they say, no need to qualify them in light of 20th century liberalism and 15th century Anabaptism. Not saying that those who hold otherwise are Anabaptists or liberals, but that's where that view comes from. Christians before the 15th century are unanimous that Baptism is necessary for salvation.