Full immersion.
If you had a cloth that was completely red, and you wanted it completely white, you would immerse it completely into a dye or bleach to turn it white. (Immerse, submerge, dunk, etc.)
Sprinkling or spritzing a bit of dye on it wouldnt work, nor would only partially submerging it.
It would have to be fully dunked to be transformed from a red cloth to a white one.
When Jesus saves us, when we believe (receive, accept, etc., ppl use different terms), but when we believe in the Lord Jesus Christ as our Saviour, we've been 'baptized into Christ', fully immersed, washed, cleansed, 'bleached', if you will.
This is why we sing...Jesus paid it all, all to Him we owe, sin had left a crimson stain, He washed it white as snow!
That is salvation, being saved by God, as a gift of His grace, through faith in the finished work of our Lord and Saviour Jesus Christ, Hallelujah! This is all the work of God, apart from water-baptism, communion wafers, titheing, or any religious rituals or good deeds on our part. Purchased with the precious blood of Jesus, adopted into the family of God, declared righteous in Christ and sealed with His Holy Spirit.
The ceremony of water-baptism SHOULD be a full immersion, as it represents what Jesus Christ did for us. He fully died and rose again. We've been fully immersed in and saved by Him, and we should be fully immersed in water indicating we've been buried with Him, and brought up from the water, indicating we are risen with Him, IN HIM.
So SHOULD be, yes, but NOT as a legalistic necessity for salvation, that negates the point of being saved by grace thru faith. Some may be baptised in different ways...maybe they CANT be dunked, or not at all.
Water-baptism is a wonderful ceremony, but a person can be saved without it.
If someone is telling you you MUST be water-baptised, or water-baptised a specific way IN ORDER TO BE SAVED, they're preaching a different, or false, gospel.
Believe on the Lord Jesus Christ and thou shalt be saved.
Celebrate His gift of salvation with a wonderful water-baptism ceremony.
Just dont turn it into a religious 'Have-to' in order to be saved, or you frustrate
the grace of God and defeat the purpose. Peace.