Baptism is an outward expression of an inward decision. Baptism is going public with your faith. It is your response to your decision of starting a relationship with Jesus. Baptism is not necessary for salvation, however it is not just a mere suggestion, it is command given by Jesus. And if Jesus himself got baptized and then told us to get baptized– well then as followers of Jesus we need to follow Him and do the same.
Baptism is like a wedding ring or like a name tag showing where your identity lies. Baptism symbolizes your old life dying, when you go under the water, and then your new life beginning, when you come out of the water.