Believer’s baptism is distinguished from infant baptism in that an infant, who has no understanding of the gospel, cannot be a “believer” in Christ. Believer’s baptism involves a person hearing the gospel, accepting Christ as Savior, and choosing to be baptized. It is his or her choice. In infant baptism, the choice is made by someone else, not the child being baptized. Those who baptize infants often teach that water baptism is the means by which the Holy Spirit is imparted to an individual. They base this idea primarily upon Peter’s words in Acts 2:38: “Repent and be baptized, every one of you, in the name of Jesus Christ for the forgiveness of your sins. And you will receive the gift of the Holy Spirit.” Those who hold this doctrine believe that the act of baptizing an infant sets the child apart and secures salvation. Nowhere in Scripture is the practice of infant baptism even implied. Some point to the few references of the apostles baptizing “households” (Acts 11:14; 16:15, 33), with the assumption that the households included infants, but this is going beyond what the text says.

In the New Testament, baptism by water was the natural result of saving faith and commitment to Jesus as Savior and Lord (Acts 2:42; 8:35–37). Since infants and small children cannot make an informed decision to profess Jesus as Lord, their baptism has no spiritual significance. If infant baptism made a baby right with God, then only children whose parents desired it would be “saved.” Those who did not have believing parents would be condemned as infants, an idea with no biblical foundation. Scripture is clear that God judges the heart of every person and judges or rewards each based on the decisions made by that individual, not by his or her parents (Romans 2:5–6, Jeremiah 17:10; Matthew 16:27; 2 Corinthians 5:10).

https://www.gotquestions.org/believers-baptism.html