The definition of baptism means to place into, submerge, soak
When a person is baptized, he is identifying with death, burial and resurrection of Jesus. Water baptism is a person acting out his faith publicly because he is saved. When a person is born again and the old man crucified, he is separated from the world and it’s values. Identifying with Jesus in baptism is then making a statement of fact that he is no longer a part of this world. (Romans 6:3-5) It is a public announcement of one’s faith in Jesus Christ!
New Testament water baptism is only valid after you’ve accepted Jesus as your Lord. (Acts 8:12, 37-39)
Let’s sum this up with the following analogy
A couple falls in love long before they are married. They make a commitment to spend the rest of their lives together even before walking down the aisle and proclaiming “I do.” Their wedding day is their proclamation to the world that they are in love and desire to live for each other forever.
This is true with water baptism, first you fall in love with Jesus and become born again and then you “walk the aisle” of baptism. So consider water baptism as your wedding day with Jesus. You are making an outward expression of your inward decision to follow Jesus.