Baptism is in FACT part of the gospel.
The Philippian jailer was told the gospel and was immediately baptized.
Repeating a command is NOT the same thing as obeying a command. John said:
1Jn 2:1 My little children, I am writing these things to you so that you may not sin. But if anyone does sin, we have an advocate with the Father, Jesus Christ the righteous.
1Jn 2:2 He is the propitiation for our sins, and not for ours only but also for the sins of the whole world.
1Jn 2:3 And by this we know that we have come to know him, if we keep his commandments.
1Jn 2:4 Whoever says "I know him" but does not keep his commandments
is a liar, and the truth is not in him,
Sins are washed away by calling upon the name not the titles.
We are baptized into HIM not THEM (
Rom. 6).
Sins are remitted by the name.
I always find it amazing that some will pray in Jesus' name.
Some will cast out devils in Jesus' name.
Some will heal the sick in Jesus' name.
etc.
But refuse to use the name in baptism.
Acts 2:38 is as much part of the gospel as the cross.