I think Zuriel is referring to full immersion baptism as a sign of Salvation, not just belief.
Correct Zuriel?
Correct. As Peter testified to the Jews on Pentecost, of Jesus of Nazareth, of his life on earth with miracles, signs and wonders, also confirming:
his death and his resurrection;
And also David’s words concerning Jesus, and that he has been “made both Lord and Christ”.
The people hearing those words obviously believed them, believing that Jesus is the Christ, for it shook them into conviction.
They knew they needed deliverance, asking “what shall we do?”
Peter commanded repentance and baptism in the name of Jesus Christ for the remission of sins, and that they would receive the gift of the Holy Ghost (Acts 2:38).
About 3,000 souls believed Peter’s words and were baptized that same day (3,000 souls÷12 apostles=each apostle baptizing about 250 souls. Whew!).
Jesus commanded his apostles to remit sins (John 20:23), and on that first day of the church they surely did.