In another thread, the subject of water baptism has intervened into the subject of the thread, and threatens to divert (
The Hope Of The World). This subject can be a contentious one, but I hope it can be approached with love on all sides.
On the side of the necessity for water baptism for salvation, certain verses were quoted in that thread by a participant, which could provide a starting point.
John 3:5,
Mark 16:16, Acts 2:38, 1 Peter 3:21
I guess the way to answer this question is to look at what the bible says. On the day that the church was birthed and it welcomed its first members what was the message given to them in answer to their question men and brethren what shall we do? Here is the reply...
Acts 2:38 And Peter said to them,
Repent and be baptized, each of you on the name of Jesus Christ to remission of sins. And you will receive the gift of the Holy Spirit. For the promise is to you and to your children, and to all those afar off, as many as the Lord our God shall call.
A few pointers for you. The question asked was one that was seeking information about their response to the information they were given. In other words "how do we follow this messiah?" The answer "Repent and be baptized in the name of Jesus (note, not the trinity).
In context, there were many religions already in operation. For many of them, you could say you followed that religion but until you were baptized by immersion (there was no such thing as sprinkling), you were not considered a genuine member of it.
So, in being told to repent and be baptized what they were being told was that if they wanted to be a genuine member of this new sect, which is what it was, they had to show it by being baptized by immersion.
So, you could join, not be baptized but not be considered a genuine member of it. Your serious intentions were evident by being baptized by immersion.
The other thing to note is that nowhere has this instruction been rescinded in scripture and the following verse in Acts 2 indicated that it was not only for those present but anyone wherever they were who joined themselves to be a genuine member needed to be baptized.
Note that originally the church was known as "The Way" and was looked upon as a sect of Judaism. It did not become a church as we know it until Antioch when the people involved were called Christians and even then that was a name thought up by unbelievers as a mark of derision.
So is baptism necessary for salvation? my answer is "If you want to be taken seriously, then yes it is. If you don't want to be taken seriously, then no it is not."
As an aside, I was living in England when the charismatic renewal hit the country in the 60s. One of the denominations that were impacted by it was the Anglican Church. You could go to an Anglican service and think you were in a pentecostal church. Many Anglican churches at this time installed baptismal equipment so they could baptize believers by immersion. They realized the whole nine yards required baptism by immersion.