What does Acts 28:26 mean?

Paul is talking to the Jewish leadership in Rome. He has explained how Jesus of Nazareth fulfills the Messianic prophecies of Moses and the prophets. Some of the Jews accept his explanation. To those who don't, Paul quotes another prophecy: this one about Jews who refuse to understand God's Word.

Isaiah served during the reigns of the Judah kings Uzziah, Jotham, Ahaz, Hezekiah, and Manasseh. He saw the northern kingdom of Israel fall to the Assyrians and prophesied Judah would fall to Babylon (Isaiah 39). This quote is taken from Isaiah 6:9; Acts 28:27 quotes Isaiah 6:10. Isaiah 6 recounts Isaiah's commissioning as a prophet. He had a vision of the Lord on His throne, flanked by seraphim with six wings each. Isaiah lamented that as a fallen human he had no right to be in the Lord's presence. One of the seraphim ceremonially cleansed Isaiah with a burning coal so that when the Lord asked for a messenger, Isaiah volunteered (Isaiah 6:1–8).

Ironically, the Lord's first words in the commissioning ceremony were a prophecy that the people would not listen to Isaiah's warnings. Isaiah primarily prophesied to Kings Ahaz and Hezekiah. Despite Isaiah's assurance that God would protect Judah from the armies of Syria and Israel, Ahaz took money from the temple treasury and paid Assyria to draw their fire away from Judah. Ahaz then ordered the priests to build a model of the Assyrian altar in the temple and burn sacrifices on it. More horrifically, he sacrificed his own sons (2 Kings 16).

Very likely, when Paul was trying to convince the Jewish leaders in Rome about Jesus, he had included references to Isaiah's prophecies about the Messiah. It was to Ahaz that Isaiah said, "Therefore the Lord himself will give you a sign. Behold, the virgin shall conceive and bear a son, and shall call his name Immanuel" (Isaiah 7:14), "Immanuel" meaning "God with us." Not long after, Isaiah prophesied the Messiah would come from Galilee (Isaiah 9:1–7).

Like Ahaz, the Jews who reject their Messiah choose to worship false gods despite God's presence with them. We aren't told what "gods" the Jews in Rome favor. It might be their position in the synagogue or the renewed but fragile peace with the Roman government who now allowed the Jews' presence in the capital. They should think more clearly, however. Despite Judah's escape from the Assyrians, about seventy-five years after Isaiah died Jerusalem fell to Babylon. About three years after Paul died, Jerusalem fell to Rome.