The Greek baptisma means 'immersion' and such is also the correct form of baptism - complete immersion in water. In 1 Cor. 10:2 the apostle Paul connects the immersion baptism with the exodus of Israel from Egypt, when "all were baptized to Moses in the cloud and in the sea." The 'immersion' in the sea was therefore a symbolic turning point separating the current life of the chosen nation in Egypt from the new life on the way to the promised land. That is why later John the Baptist practices the baptism of immersion in the waters of the Jordan as a sign of repentance that separates the life of a sinful man from the new life of one who recognizes his sin and turns to God for its repair (repentance, Greek metanoia - change of thinking). Also, our Lord in his last words addressed to his followers connects baptism with a change of thinking - the nations subjected to baptism are to act in the Lord's teaching and "observe all things, whatever I commanded you" (Mt. 28:19,20). In the New Testament, baptism as a symbol of the life 'before' and 'after' also points to consecration of those believers who 'live no more to themselves, but to Him who died for them and was raised' (2 Cor. 5:14,15).
The change symbolized in water baptism is visible in more detail in its two phases: immersion and rise. In Rom. 6:1-6 the apostle Paul connects the immersion element with burying of the body. The concept of the body in the Bible means not only the material body, but also the character - scripts of behaviour written in the (nervous system of the) material body. Similarly, the concept of 'the body of sin' refers to those scripts that lead to violating God's law. The baptism in the element of immersion symbolizes, therefore, the "burial" - subjecting to death and destruction - of our sinful character. From this death, however, we are to be raised to the 'newness of life', to become the body of Christ instead of the body of sin - so that our personality fully reflects the rightful qualities of the Lord's character. The submission to the baptism by a believer is therefore a symbolic expression of his metanoia - a change in the thinking one has experienced, leading from the death of the current personality to the birth of a new person created in the image of Jesus Christ.