Why should we worry about other doctrines after Acts 2:38 if we can't even get Acts 2:38 right?
"Depart from me, I NEVER knew you" applies here.
Well yes, I agree with that.
So, if we cannot convince folks to accept the first gospel sermon by Peter, Acts 2:38.
Then there is no hope that they will be saved.
But also they must know there is more to Peter's gospel than what is told by the scriptures in Acts 2:38.
There is not one verse in the new testament that teaches every requirement by Jesus to be saved.
John 3:16 is not the whole gospel
Acts 2:38 is not all the requirements to be saved.
You have to study all the conversions in Acts to see the whole picture on what Jesus' gospel includes in being saved.
Even Jesus did not teach everything one must do to be saved in one or two verses, Mark 16:15-16 for example.
Jesus did not mention repentance in Mark 16:16. But He did by the mouth of Peter in Acts 2:38.
Here is every requirement/command to be saved in Jesus' gospel.
After a person is saved. There is more commandments for Christians to obey. But not to be saved.
Believe Acts 2:37 ; Mark 16:16
Repent of sins Acts 2:38
Confession of faith in Christ, Acts 8:37 ; Romans 10:9-10 ; Matthew 10:32-33
Water immersion for forgiveness of sins, Acts 2:38 ; Acts 22:16 ; Mark 16:16
All these commandments are of the same importance in Jesus' gospel unto salvation.
If one of these commandments is not obeyed
Then the person has not obeyed the true gospel of Jesus Christ.
I can make a false gospel out of water baptism just as I can out of faith alone.