Baptism is the first step of obedience following salvation. It is an outward profession of faith. By mirroring the death, burial, and resurrection of Jesus, Baptism proclaims to everyone that you belong to Jesus.
What shall we say then? Are we to continue in sin that grace may abound? By no means! How can we who died to sin still live in it? Do you not know that all of us who have been baptized into Christ Jesus were baptized into his death? We were buried therefore with him by baptism into death, in order that, just as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life.
(Romans 6:1-4).
Having been buried with him in baptism, in which you were also raised with him through faith in the powerful working of God, who raised him from the dead.
(Colossians 2:12)