Water baptism is not a “requirement” for salvation since God does the saving, but is something Christians get to do in order to help them.
New Christians may not tap into everything that is available to them to help them experience the transformation:
I know that I needed everything God could provide to assure me of my conversion, both outwardly and mentally. God wants you to physically feel the experience of what is going on Spiritually.
You need to add to your conversion a definite time place and physical experience, which God has provided for you. We talk about being “Born again”, which comes from Nicodemus encounter with Christ (John 3 :1-21):
Being “born again” is what Jesus told Nicodemus he need to do. This requires some thinking, because Jesus does not address the questions or comments that are verbalized, but directs his comments to the persons next step in their personal spiritual development (what is on their heart spiritually). Jesus is not making some general philosophical statement (like Buddha might make) but is always addressing the audience He is talking to. We have to get into the context.
What did Nicodemus need to do next in his spiritual development?
What does Nicodemus need to be doing next? (study the Old Testament, become one of the followers of Jesus right then and there, Confess, repent, etc.)
The first thing Nicodemus might do at least is what he already knows he should do? Is that not where you would start? So what is that?
Since Nicodemus is still part of the Sanhedrin, he would not have been immersed baptized by John’s baptism. That would have got him thrown out of the Sanhedrin, but being smart Nicodemus would know he should be baptized.
John’s baptism would have been a hot topic among the religious scholars, yet the answer was obvious and they all know it (remember Jesus using it against them and causing them to quit asking him questions?)
Jesus is not going to hand out the answer to Nicodemus, since Nicodemus knows the answer, but he will make Nicodemus think about it hard, since it would already be on his mind.
Christian water baptism as seen in scripture seems to fit the “born again” scenario Christ was talking about since it: Is always adult (there are only two examples that “might include infants” but nothing definite, all the others are adult believers) water immersion to be a physical outward representation of what had or is happening spiritually in the person being baptized. It is mainly to help the individual being baptized to better grasp what is going on, but it can “witness” to others observing the baptism. It has the elements of going down under the water (burying the old man), placing your dependence in another; the person baptizing you (surrendering your life to God), being washed (having your sins washed away), rising out of the water (rising from the old dead body), and stepping forth out onto the earth (a new person). The person is walking out into the hugs of his new family. It is also a sign of your humility, since it is a humbling act anyone can simple allow someone to do it to them (so not a work) and since humility has been shown in the accept of charity (God’s free gift of undeserving forgiveness) it should just support and add to the memory of that acceptance. To refuse Christian water baptism when it is readily available might mean you are not ready to handle other responsibility like having the indwelling Holy Spirit and you are hurting yourself.
Why not be baptized again (there is no rule against this) to experience all you can from being baptized?
Yes, Ro. 10 is silent about baptism, but silence is not a proof for anything and baptism was not the topic being discussed, the Jews had to believe first, so baptism would be down the road.
Is the real problem with humility, since adult water baptism is a humbling act?
Is the problem with “witnessing” since baptism help other Christians remember what they went through?
The whole “argument” about the “one” baptism having to be “spiritual baptism” so we do not need to (or even shouldn’t) be water immersed is not supported by scriptural examples, since everyone that was “baptized” by the Holy Spirit seems to have also been water baptized.
