The Ephesians 4 reference can be taken as baptized in the Holy Spirit since we know Peter mentions that in Acts. The preponderance of the scriptural evidence shows those who proclaimed Jesus Christ were then baptized. It goes hand in hand it was never an either or other than the repentant thief who confessed directly to Christ.
I don’t know why some come out and state you don’t need to get baptized or say baptism doesn’t save. Well the act itself does not because we see Simon Magus in Acts 8 was baptized but did not receive the Holy Spirit. The evidence shows that those who responded to the preaching of the Gospel in faith got in the water.
You may want to also look at the 1 Peter 3:21 in context as well. If Peter is truly saying there the act of baptism saves it contradicts the previous and following verses. You would also have to admit there were two gospels preached if you believe the act of baptism saves. That is why we should never base entire doctrines on a couple of verses especially without looking at the context. And we should all know the Gospel established by Jesus Christ was this:
Luke 24:45-47 NASB
Then He opened their minds to understand the Scriptures, and He said to them, “Thus it is written, that the Christ would suffer and rise again from the dead the third day, and that repentance for forgiveness of sins would be proclaimed in His name to all the nations, beginning from Jerusalem.
I would also point out that there were many Disciples of Christ who in all likelihood were baptized who “went back and walked with Him no more”. Scripture tells us “Jesus knew from the beginning who they were that believed not, and who should betray him.” Then of course there was Judas. Who would doubt that he was baptized? It seems from Jesus words that it was the believe part that was the key.
Immediate and larger context, and seek to go wherever the truth leads, Scripture compared with Scripture. What is theologically stated is that in conversion faith is counted for righteousness, versus merit (Rm. 4:4-6) and by believing one is forgiven, having hearts purified by faith, (Acts 10:43ff; 15:7-9) for "with the heart man believes unto righteousness," yet "with the mouth confession is made unto salvation." (Rm. 10:10)
And as said, there is essentially no difference btwn confessing the Lord Jesus by moving one's tongue versus moving on's legs to be baptized, or for that matter moving neurons in one's brain to believe on the Lord Jesus. All are volitional responses, enabled by God who also moves man to do so. But which does not constitute salvation by works, as while a response is involved, these do not earn one salvation, and in fact what man has earned is damnation.
What if one believed and immediately died before he could manifestly confess the Lord Jesus? He would still be saved as it is the faith that results in confession that appropriates justification. But since faith and confession go together (as seen in Rm. 10:1-14) the former begetting the latter, and as true confession requires saving faith, thus the promise can be made that "whosoever shall call upon the name of the Lord shall be saved." (Romans 10:13) Likewise Acts 2:38. For this is essentially the same thing as saying, "For the scripture saith, Whosoever believeth on him shall not be ashamed." (Romans 10:11)
Likewise in countering the idea that a dead, inert faith justifies, it can be described "how that by works a man is justified, and not by faith only," that meaning by the kind of faith that produces works. Yet if James means that one cannot be justified until he manifests works, then Cornelius and household were not justified when they were born again, nor can there be any death bed conversions by those unable to do manifest works.
For as an inert salving faith is in contradiction to Scripture, so is salvation that excludes justification by faith until he does manifest works. Yet to refuse to obey what faith calls us to do is a denial of faith, which a practicing believer repents from when convicted. For to repent of such disobedience is evidence of faith. And there is a difference btwn sinning as a believer seeking to live according to the light he has ,and who thus repents when convicted of sin, versus one who has wickedly departed from his Lord "in departing from the living God." (Heb. 3:12) Thus even after David's adultery and first degree murder, he could say, "For I have kept the ways of the Lord, and have not wickedly departed from my God." (2 Samuel 22:22)