Let's back up
"Did you receive the Holy Spirit when you were baptized?" Paul asks the believers in Ephesus.
"Uh, what's the Holy Spirit?" they reply.
If you are Paul, what do you ask now?
"So tell me, into what, exactly, were you baptized?"
"Well, water. Yes, that's right, we were baptized in water."
"That's not exactly what I meant," Paul says.
"Oh! You're looking for a theological answer. We were baptized into John's baptism."
Paul furrows his brow. "Looks like we need to back up a step or two. John's was a baptism for repentance, to get ready for Jesus." And presumably he says a bit more, too.
"Oh," they reply, "now we get it," and they are all baptized again. And this time they do get it: they receive the Holy Spirit with signs and wonders attending. At the conclusion of the service there are 12 more people in Ephesus—like those first 12 and 108 in Jerusalem—with the Holy Spirit raining on them and reigning among them, making them new and powerful witnesses for the gospel.
This text is funny, but it's also a little eerie. It sounds like conversations I sometimes have with church members, lifelong Christians who can be just as stumped as the Ephesians about the basics of the faith. "Let's back up," I find myself saying. Who preached to these people, anyway?
In Ephesus it was Apollos, whose silver-tongued presentation was not entirely accurate. Priscilla and Aquilla purportedly straightened him out, but not before he had set the stage for this conversation between Paul and the believers.
I am sometimes not so charitable as Paul, who seems not to have trashed his predecessor for his obvious diminutions. That said, I wish my remediations had as dramatic an effect as Paul's—not necessarily the speaking in tongues, but the speaking, or prophesying, about the faith.
Jesus and John were remarkably similar: both preached the kingdom of God, called disciples, ran afoul of the authorities and died young. But there were crucial differences between the cousins, especially regarding the kingdom of God. Leander Keck used to say that while the Gospel of Mark makes a clear distinction between Jesus' preaching and John's, much Christian preaching misses this difference—and sounds more like John.
Too often what's preached is that we need to do things to make ourselves worthy, to get ready for the kingdom—which is coming, dispensationally or otherwise. It's harder to see, believe and preach that the kingdom has already drawn near, in spite of or even because of our unworthiness. Our repentance doesn't summon the kingdom. Instead, we are able to repent—and will want to—because God has already inaugurated the kingdom among us.
Forgiveness—as Jesus announced it, and especially in Mark—comes before repentance. It's this message that brought the criticism that eventually took Jesus down.