To make it simple, as a child, you took a bath; as an adult, you can freely choose to die to your old self, burying your sin in the grave (water) and rising from that grave a new, clean creation in Christ. This is a symbol of what Jesus has already done for the believer and it is the believer’s way of publicly proclaiming the transformation.
I truly mean no disrespect to faiths that teach baptism of babies. But, nothing in Scripture says to baptize an infant. An infant cannot make a choice. The Bible says that to all who believe, He gives the right to be sons of God. First John 1:9 says, “If we confess our sins, he is faithful and just and will forgive our sins and cleanse us from all unrighteousness.” A baby can neither believe nor confess.
So, I would say that, as a new creature in Christ, absolutely go ahead and get baptized. It will mean so much to you because it will be something that you can remember and cherish as a symbol in your own life of what Jesus has done for you.
Check out what the apostle Paul has to say in Romans about baptism:
“What shall we say then? Shall we continue in sin, that grace may abound? God forbid. How shall we, that are dead to sin, live any longer therein? Know ye not, that so many of us as were baptized into Jesus Christ were baptized into his death? Therefore we are buried with him by baptism into death: that like as Christ was raised up from the dead by the glory of the Father, even so we also should walk in newness of life. For if we have been planted together in the likeness of his death, we shall be also in the likeness of his resurrection” (Romans 6:1-5).
Baptism is more than getting into the water and getting wet. When a Christian is baptized, they are identifying with the death, burial, and resurrection of our Lord Jesus Christ.