I was in a large main-stream type church years ago. The pastor had a PHD in theology, and he said that Baptism was: "An Outward Expression Of An Inward Work"
This was a very intellectual sounding explaination and sufficed for a time.
Since then I have met many professing Christians that agree with this explaination.
I have noticed quite a rub over the years between different groups. Even though most mainsteam groups believe that you don't have to be Baptized to be "saved", there is much arguing and disagreement about whether you should be sprinkled or submerged.
If in the Bible it says it doesn't really matter; then it does not. But, if in the Bible it says it does matter; then it does.
There are elements that are a part of our approach to God and are necessary for full Bible salvation.
I am talking about the Blood, the Water, and the Spirit.
Also the ONLY true and saving gospel of Jesus Christ is: The Death, the Burial, and the Ressurection of Jesus Christ. You REPENT of all of your sins there is a DEATH or dying out. Then you are BURIED in a watery grave ( In the NAME of Jesus Christ) for the remission of your sins. You then can receive the GIFT ( in-filling, or baptism) of the Holy Ghost.
If you've never been buried in water In the NAME of Jesus Christ, you need to. If you've been baptized in any other formula (In the name of the Father, and of the Son, and of the Holy Ghost) you basically just got wet.