Baptism is an outward expression of the inward decision to place your faith and trust in Christ as the leader of your life. Being lowered into the water symbolizes dying to your old self, and then being raised into new life with Him.

"Therefore go and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit,  and teaching them to obey everything I have commanded you. And surely I am with you always, to the very end of the age.”
Matthew 28:19-20

This is new life!