I’m glad to see you back as well.
Let us look at water baptism AFTER the Lord's death, burial and resurrection. We do know that before a person could be baptized with water that person must first believe, as witnessed by the following exchange between Philip and the eunuch:
I agree, baptize believers. That’s what all the apostles did including Paul.
Before the eunuch was baptized with water he was already "born of God" because he believed that Jesus is the Christ, the Son of God:
"Whosoever believeth that Jesus is the Christ is born of God..For whatsoever is born of God overcometh the world: and this is the victory that overcometh the world, even our faith. Who is he that overcometh the world, but he that believeth that Jesus is the Son of God?" (1 Jn.5:1,4-5).
There can be no doubt that the eunuch received eternal life and was "born of God" before he was baptized with water so we can know that being baptized with water does not contribute in any way to anyone being saved.
I would suggest your making a leap here. John is writing to people who are already Christians and having believed were baptized as instructed by Jesus and carried out by the apostles.
I would suggest we go back and look at what Jesus said and what the apostles taught and did to convert people.
As for being “born of God” what did Jesus tell Nicodemus.
“unless one is born of water and the Spirit he cannot enter into the kingdom of God”
After his D,B&R Jesus instructs the apostles on how to make Christians.
Matt. 28:19
Go therefore and make disciples of all the nations, baptizing them in the name of the Father and the Son and the Holy Spirit,
We see the apostles do just that and we see people born of water and Spirit just as Jesus said.
Acts 2:38
Peter said to them, "Repent, and each of you be baptized in the name of Jesus Christ for the forgiveness of your sins; and you will receive the gift of the Holy Spirit.
Now let us look at this verse:
"He that believeth and is baptized shall be saved; but he that believeth not shall be damned" (Mk.16:16).
Here the Lord is not saying that a requirement for salvation is baptism with water, but instead He is describing those who will be saved.
When we look at the parallel passage to this one, Matt. 28:18-20, we see baptism is how people become Christians and it’s how we call upon his name.
Consider the conversion of Paul. After he had been blinded, praying for 3 days and nights, having hands laid on him receiving his sight and filled with the Spirit, he still had something to do. Ananias says
“Now why do you delay?”
What was it he hadn’t done yet? Believed, confessed or repented? He still needed to be baptized and it says to wash away his sins calling on his name. He still had his sins because he wasn’t added to Christ yet, Acts 2:41
So then, those who had received his word were baptized; and that day there were added about three thousand souls.
All we see him do is be baptized.
Acts 22:16
Now why do you delay? Get up and be baptized, and wash away your sins, calling on His name.'
Baptism is how we call on upon Jesus’ name. It’s how we become Christians by being baptized “
in the name of Jesus”.
Consider this. Here Paul finds disciples who believed in Jesus and were baptized but with John’s baptism. Paul asks them, did they receive the Holy Spirit when they believed. Why would he ask that if it’s given upon belief? When he finds out they didn’t know about the Holy Spirit, he asks them about their baptism. Why would he do that if there is one baptism and it’s done at belief? Shouldn’t he be asking about the gospel they were taught or did they believe it? We see that he doesn’t just give them the Holy Spirit without doing something first. He baptizes them
in the name of Jesus. Then he gives them the Holy Spirit by laying his hands on them, Acts 19:1-6.