Well, i don’t want to go too far down a rabbit trail… but I generally endeavor to avoid doing theology or developing a positive case based on what the Bible doesn’t say. But i can say with certainty that I myself will find any case so developed unconvincing in the extreme.
“Changing his approach?” What Luke does actually say is that it was the talk specifically about bodily resurrection that caused his audience to scoff… are we actually suggesting that Paul somehow began at this point to refrain from speaking about the resurrection? Or that we should do likewise?
Finally, to bring this back to the point of this thread… i would humbly caution that the approach you’re using about this passage seems to me to be exactly what i fear about modern theology, apologetics, and the like in general… i.e., using human standards and measures about “effectiveness” to determine the merit of an approach, rather than Christ’s own standard.
By the standard you’re suggesting (relatively few converts, no established church), what would we say about many events or activities in Christ’s own ministry?
Jesus’s teaching in his own hometown? Did not go very well, they continued in their unbelief such that Jesus marveled at it, he couldn’t even perform many miracles there.
Jesus preaching about himself being bread of life? Did not go very well, many disciples gave up and no longer followed him.
Jesus interacting with the rich young ruler? Did not go very well, this man didn’t convert and walked away.
Jesus preaching in parables? Did not go very well, even by his own admission he did this so that they would not “turn and be forgiven”.
Jesus healing the demoniac? that did not go very well, the entire city asked Jesus to leave, the only person apparently converted was only the (former) demoniac himself.
Sorry to get on a soap box, but this is one topic i’m (obviously) particularly passionate about. We evangelize/apologize in a way that honors our king and is measured by his pleasure in our proclamation, not on human/worldly standards of “success”… I hope it should be clear as crystal that when many people did not respond to Jesus own preaching and miracles, but persisted in unbelief, we probably should not attribute this to Jesus failing to do evangelism the “proper” way". Perhaps we could give the same courtesy to Paul?