This thread is not meant to suggest the only, or ultimate reason for water baptism. But like many commands in the Bible, suggest a lesson.
First off, when a convert accepts the call to be baptized, they are not submitting to being cleansed by the H2o they will be submerged in. If someone is baptized in a swimming pool, the water doesn't transform into a divine detergent. It remains the same water with the same chlorine. If it's a river or lake, it will remain the same murky water, and probably won't make much difference to the nearby fish. Water baptism itself won't save anyone's soul. It's not ultimately necessary for salvation. If it was, the thief on the cross who repented would not have been allowed entrance into paradise.
It is a symbol of being washed, cleansed, and made pure. But the water itself does no spiritual cleansing. Baptism is symbolic, and an act of obedience.
When one becomes a believer, the point where God meets them in a divine way, they find they have a calling.
Ephesians 4:1 New International Version (NIV)
Unity and Maturity in the Body of Christ
4 As a prisoner for the Lord, then, I urge you to live a life worthy of the calling you have received.
Unity and Maturity in the Body of Christ
4 As a prisoner for the Lord, then, I urge you to live a life worthy of the calling you have received.
To embark on that journey requires obedience and to follow a spiritual leading. Whether that calling is to become a minister, or a witness in a secular field, etc., it's a spiritual journey that requires the aforementioned. If someone encounters the living God, gives their life to Him, etc., logically if that person refused to be baptized, there would probably be something seriously wrong. Why would they refuse a commandment which is often made in public to some degree, usually relegated to other believers? If that person, for instance, expressed a desire to get involved in a ministry that's part of the church that would be baptizing them, it would certainly be a red flag for the church leaders because it would appear that this person would ultimately refuse leadership. And of course ultimately, it would be a pretty sure sign that the person would not follow the leading of the Holy Spirit in terms of fulfilling their calling (running the race).
This principle of relatively simple obedience can be applied to a number of ceremonial practices and observances mandated in the Bible, like communion. Again, nothing magical about the juice and wafers. They do not transform into the literal body and blood of Christ (are you listening Deb8able?). But the obedience serves a similar purpose of simple obedience to Christ, and the Body of Christ. And serves a purpose of obedience in
examining our hearts.