I'm sorry, but if it is impossible to enter the Kingdom of Heaven without baptism, I'd say it's pretty obviously a requirement for salvation.
Where in the Bible does it state that this was the reason Jesus was baptized? As far as I know, He was baptized in order to "fulfill all righteousness" -- i.e. because His Father required it of Him. The fufillment of righteousness was His incarnation (God in the flesh, His ministry while on earth as a physical man, His death through cruxifiction and His ressurection. That was God's will. Also, there are many verses in the Bible regarding salvation, and not many (if more than one) reinforce the need for a water baptism as a requirement for salvation.
I believe that, at baptism (which must be preceded by faith in Jesus Christ and repentance), we enter into a covenant relationship with our Savior. We covenant with Him to keep His commandments and He covenants with us to offer us forgiveness and the chance to be reconciled to God. A water baptism is a symbolism of repentence and the cruxifiction of the old person and resurrection of the new person in Christ. It is not a requirement for salvation. We do honor Christ through this ritual, but the spiritual baptism (accepting Christ through faith) is what provides salvation.
So, if you think that baptism by water refers to one's physical birth, why do you think Jesus bothered to be baptized a second time by John? If He'd already been baptized by water once, why did He feel the need to be baptized by water a second time? Also, if you believe in the doctrine of the Original Sin, as I suspect you do (by the way, I don't), how can we simultaneously be born in sin at the same instant as we are born (i.e., in your opinion, "baptized of water")? I've stated what the fulfillment of righteousness was based on, and it wasn't a water baptism, but more to do with His ministry, death and resurrection. That is what impacted people's lives, not His baptism with John. The context of Scripture I was referring to was in direct response to Nicodemus's question regarding being "born again".
I have and I do. By the way, in case you haven't heard, faith without works is only a dead faith anyway.
Regards,
Kathryn