The Biblical response to ACTS 2:38

[Aquila]

There's a question I've not heard anyone ask...

What is the purpose of the baptism of the Holy Ghost?

We know that repentance coupled with calling on the name of the Lord in water baptism remits our sins. However, the purpose of the Holy Ghost was explained by Jesus,

(Acts 1:4,5,8 KJV)
(4) And, being assembled together with {them}, commanded them that they should not depart from Jerusalem, but wait for the promise of the Father, which, {saith he}, ye have heard of me. (5) For John truly baptized with water; but ye shall be baptized with the Holy Ghost not many days hence. (8) But ye shall receive power, after that the Holy Ghost is come upon you: and ye shall be witnesses unto me both in Jerusalem, and in all Judaea, and in Samaria, and unto the uttermost part of the earth.

The purpose of the baptism of the Holy Ghost is empowerment.

It's important to understand that the Holy Ghost is active in one's life at the moment of repentance, for how can one repent accept they believe that Jesus is Lord?

1 Corinthians 12:3
Wherefore I give you to understand, that no man speaking by the Spirit of God calleth Jesus accursed: and that no man can say that Jesus is the Lord, but by the Holy Ghost.

We know that the Holy Ghost was received and active in the disciples prior to Pentecost...

John 20:22
22 And when he had said this, he breathed on them, and saith unto them, Receive ye the Holy Ghost:

I believe that we often misunderstand the purpose of the Baptism of the Holy Ghost. I believe the purpose is spiritual empowerment to witness, pray, and be led into truth. I see it like this...

Repentance - Justifies one before God.
Water baptism (while calling on the name of the Lord) - Washes away our sins.
Baptism of the Holy Ghost - Empowerment.

Justification, forgiveness, and empowerment. That's the result of Acts 2:38.

I wouldn't go as far as to say that someone who hasn't received the baptism of the Holy Ghost is lost... but I would go as far as to say that they are not walking in the entirety of what Jesus purchased for them at Calvary.