"It is by grace that we are saved, not by any work we do, or lack thereof, so why would the failure to be baptised, after you've made a concious decision to accept the Lord as Savior, keep you out of heaven."
But Arduro can always reply, "Then he or she was never saved at all." That is, those who will be saved are only those (and a subset of those, at that) who will be baptised. Because this person died on the way to be baptised, we know that he or she was not really saved.
Person A may believe that he or she is saved, but if the future-tense statement, "person x will be baptized" is false, then A is not really saved; A must be either self-deceived, or lying to us.
You see, it is not because A is baptised that he or she is saved; he or she is not saved because of the act of baptism; baptism has no salvific effect. No, it just happens that as a blunt, matter of fact, God has only elected to salvation those for whom the future tense statement is true, "person x will be baptized." We don't need to know why God made this decision, or whether God has any reason at all for having made this decision - it is just the way things are. Anyone else who thinks they are saved are either self-deceived or lying to us.
Of course this fits perfectly with the claim that one can never know whether he or she is saved. But even if it is possible to know for certain that we are saved, it could always be the case that we are merely self-deceived into believing that we know we are saved when in fact we are not.
The question then really just becomes academic.
I don't believe there is any effective counter to this other than to show that the passages in question (especially John 3:5) are somehow in fact not meant to indicate "those who are saved are those for whom it is true: person x will be baptized." Appealing to intuition about what God "would" or "should" do "because he is loving" will get you no where, because intution is a faulty guide to understanding God's righteous requirement.
But essentially what I am saying is that the link you have provided fails to demonstrate that baptism is not required. Even the premise, for example, "we know we are saved by faith alone," is completely irrelevant, because the baptism-only proponent does not claim that baptism has salvific effect; no, it just happens that as a matter of fact, those who will be saved are only those who will be baptized - it is just the same as if it were the case, as a blunt, matter of fact, God had decided to elect only those for whom the future-tense statement is true, "person x will click his or her heels together three times." Clicking one's heels together has no salvific effect.
Unless John 3:5 does not refer to baptism, the link provided is ineffectual. The argument that John 3:5 does not refer to baptism seemed very weak.
Personally, I hope that baptism is not required for salvation, but that is little consolation if it is in fact required.
I'd like to be wrong; I have never been baptized. If you are concerned about it, technically you should be able to baptize yourself in your bathtub.
