The early Church would have strongly disagreed with you that there was no correlation. This included all those responsible for affirming which books were in the New Testament. Did God allow His people to be wrong about this for nearly approx. 1500 yrs? If so what does that say about God? There is not one Bible verse that says baptism is symbolic; rather, there are many which explicitly state that baptism is salvific in nature.
Acts 2:38 - Peter commands them to repent and be baptized in the name of Jesus Christ in order to be actually forgiven of sin, not just to partake of a symbolic ritual.
Mark 16:16 - Jesus said “He who believes AND is baptized will be saved.” Jesus says believing is not enough. This is because baptism is salvific, not just symbolic. The Greek text also does not mandate any specific order for belief and baptism, so the verse proves nothing about a “believer’s baptism.”
John 3:3,5 - unless we are “born again” of water and Spirit in baptism, we cannot enter into the kingdom of God. The Greek word for the phrase “born again” is “anothen” which literally means “begotten from above.”
Acts 16:15; 31-33; 18:8; 19:2,5 - these texts present more examples of people learning of Jesus, and then immediately being baptized.
Acts 9:18 - Paul, even though he was directly chosen by Christ and immediately converted to Christianity, still had to be baptized to be forgiven his sin. This is a powerful text which demonstrates the salvific efficacy of water baptism, even for those who decide to give their lives to Christ.
Acts 22:16 - Ananias tells Paul, “arise and be baptized, and wash away your sins,” even though Paul was converted directly by Jesus Christ. This proves that Paul’s acceptance of Jesus as personal Lord and Savior was not enough to be forgiven of his sin and saved. The sacrament of baptism is required.
Rom. 6:4 - in baptism, we actually die with Christ so that we, like Him, might be raised to newness of life. This means that, by virtue of our baptism, our sufferings are not in vain. They are joined to Christ and become efficacious for our salvation.
1 Cor. 6:11 - Paul says they were washed, sanctified, and justified in the name of the Lord Jesus, in reference to baptism. The “washing” of baptism gives birth to sanctification and justification, which proves baptism is not just symbolic.
Heb. 10:22 - in baptism, our hearts are sprinkled clean from an evil conscience (again, dealing with the interior of the person) as our bodies are washed with pure water (the waters of baptism). Baptism regenerates us because it removes original sin, sanctifies our souls, and effects our adoption as sons and daughters in Jesus Christ.
1 Peter 3:21 - Peter expressly writes that “corresponding to Noah’s ark, now saves you; not as a removal of dirt from the body, but for a clear conscience. “ Hence, the verse demonstrates that baptism is salvific (it saves us), and deals with the interior life of the person (purifying the conscience, like Heb. 10:22), and not the external life (removing dirt from the body). Many scholars believe the phrase “not as a removal of dirt from the body” is in reference to the Jewish ceremony of circumcision (but, at a minimum, shows that baptism is not about the exterior, but interior life). Baptism is now the “circumcision” of the new Covenant (Col. 2:11-12), but it, unlike the old circumcision, actually saves us, as Noah and his family were saved by water.
Mark 16:16 - Jesus says that he who believes and is baptized will be saved. However, the Church has always taught that baptism is a normative, not an absolute necessity. There are some exceptions to the rule because God is not bound by His sacraments.
Luke 23:43 - the good thief, although not baptized, shows that there is also a baptism by desire, as Jesus says to him that he will be in paradise. It should also be noted that when Jesus uses the word “paradise,” He did not mean heaven. Paradise, from the Hebrew “sheol” meant the realm of the righteous dead. This was the place of the dead who were destined for heaven, but who were captive until the Lord’s resurrection. Hence, the good thief was destined for heaven because of his desire to be with Jesus.
Matt. 20:22-23; Mark 10:38-39; Luke 12:50 - there is also a baptism by blood. Lord says, “I have a baptism to be baptized with” referring to His death. Hence, the Church has always taught that those martyred for the faith may be saved without water baptism (e.g., the Holy Innocents).