A couple of weeks ago, I found myself chatting with a friend online about a very familiar subject to me, the meaning of the phrase "the gift of the Holy Spirit" in Acts 2:38 and 10:45. I literally spent decades arguing the point with my father, as part of our ongoing discussion about the nature of the Holy Spirit generally. Because the subject does come up sometimes, I thought others might find my conclusions on the matter to be of interest.
Two Different Meanings
In order to understand the issue, I think we first have to acknowledge that the same phrase used in different places in Scripture does not necessarily have the same meaning every time it is used. For example, "the kingdom of God" in Luke 17:20 (which is not accompanied by signs) does not mean the same thing as "the kingdom of God" in Luke 21:31 (which is distinguished by the signs that accompany it). I think we can presume that the same phrase always means the same thing, but that presumption can be overturned by evidence from the context.
Indeed, I think that we must reject this presumption in the case of "the gift of the Holy Spirit". In Acts 10:45, the meaning of the phrase is clear. It's a reference to the miraculous spiritual gift of speaking in tongues that has just been poured out on the Gentiles of the household of Cornelius ("the Holy Spirit fell on all" in Acts 10:44).
Note that Peter's conclusion upon observing this outpouring is not that the Gentiles have already been saved. It is that they need to be baptized. Here as elsewhere in Scripture, the possession of a miraculous spiritual gift does not imply that the possessor is in a right relationship with God.
Gifts or Salvation?
In Acts 2:38, the matter is less clear-cut. Grammatically speaking, "the gift of the Holy Spirit" can refer to the Holy Spirit given as a gift. However, it can also refer to a gift given or bestowed by the Holy Spirit. For instance, "the gift of God" in Acts 8:20 does not refer to God giving Himself as a gift; it refers to a gift bestowed by God (specifically, the ability to impart miraculous spiritual gifts through the laying on of hands).
As a result, I think we may at least entertain the notion that the gift of the Holy Spirit in Acts 2:38 is not actually the Holy Spirit Himself, but rather is something imparted or promised by the Holy Spirit. Contextually, there's an obvious candidate for this gift: salvation. This is the first gospel sermon, after all, not the first sermon on spiritual gifts!
The argument that Peter is promising salvation, not gifts, begins with the prophecy from Joel recorded in Acts 2:17-21. Peter argues not only that the apostles speaking in tongues is a fulfillment of this prophecy, but also that the prophecy's fulfillment points to a greater promise. Because of the tongue speaking, the audience has reason to conclude that everyone who calls on the name of the Lord will be saved.
Throughout the rest of the sermon, Peter uses tongue-speaking only to prove that Jesus is the Lord upon whose name we should call. Why, then, would the big payoff promise in Acts 2:38 be about something as unimportant as spiritual gifts?
Solving the Wrong Problem
Second, if Peter is promising his Jewish audience spiritual gifts rather than salvation, he's solving a problem they don't have. After he finishes his sermon, they don't respond by saying, "Wow! Tongue speaking is really cool! Can you help us to do that?" Instead, they exclaim, "What shall we do???" because they realize that they have crucified the Son of God. They've got a hammer the size of the universe coming down on their defenseless heads, and they desperately want to get out from under it.
Salvation is what they're looking for, and Peter knows that perfectly well, so it's reasonable to conclude that everything in his answer is about giving them. . . salvation. If he's talking about spiritual gifts instead, he's basically trying to sell carpet-cleaning services to somebody whose house is on fire. The apostles were smarter than that!
Third, if "the gift of the Holy Spirit" in Acts 2:38 is about spiritual gifts, Peter is overpromising. His words make clear that the gift of the Holy Spirit is an immediate consequence of being baptized for the forgiveness of sins. Do this, and you'll get that. If this is not clear enough, he adds in Acts 2:39, "for the promise is for you and for your children and for all who are far off, everyone whom the Lord our God calls to Himself." If the gift of the Holy Spirit is spiritual gifts, everybody who is baptized for the forgiveness of sins should receive spiritual gifts before they finish toweling off.
This doesn't happen, and it didn't happen even in the first century. We know from Acts 2:47 that everybody who was baptized was saved, but there's no evidence that everybody received spiritual gifts at the same time. If they did, why is everybody so devoted to the apostles' teaching in Acts 2:42? Generally, we see spiritual gifts in non-apostles concentrated in places like Antioch and Corinth—places where the apostles weren't.
Similarly, in Acts 8:16, we learn that the Samaritans who listened to Philip's preaching are baptized, but they don't receive spiritual gifts until Acts 8:17 when Peter and John come down from Jerusalem and lay their hands on the new disciples. Throughout the New Testament, spiritual gifts and the laying on of hands are connected. Salvation and water baptism are connected. Spiritual gifts and water baptism aren't.
As I noted earlier, there is a presumption that "the gift of the Holy Spirit" means the same thing in Acts 2 as it does in Acts 10. However, the textual evidence doesn't support that presumption. It undermines it. The gift of Acts 2:38 is the gift of salvation, and the promise of Acts 2:39 is the promise that all who call on the name of the Lord will be saved, and it's for everybody who hears the gospel. God isn't offering us all something as splashy as the gift of tongues or prophecy. Instead, what's on the table is something far better — life through the risen Christ.