Herod Agrippa I generally spent his three years in power
accommodating and even protecting the Jewish religion and respecting
the Jewish God; the Jews respected him for it. The ancient historian
Josephus fills in some of the details about this event not mentioned
in Acts (Antiquities 19.8.2 343–361 < ). According to Josephus, on
the second morning of games Agrippa has inaugurated for Caesar,
he addresses the audience wearing clothes made of silver. The
sunlight catches the silver, and he glows like the Phoenician sun
god. The audience goes mad, saying, "The voice of a god, and not
of a man!" (Acts 12:22).

Ordinarily, Agrippa might have denied their praise, but this day he
hesitates. Perhaps he's caught up in the games. Perhaps he wants to
display his glory to his antagonists from Tyre and Sidon (see Acts
12:20). Either way, he has made himself somewhat of a religious
leader among God's people, and God will not stand for it. Agrippa
is immediately overcome by severe pains in his abdomen and
dies. Josephus indicates this involved five days of agony. Adoring
Jews suspect poison. Modern researchers have many theories, but
nothing concrete (Josephus' Antiquities 19.8.2 343–361).

Agrippa I had many similarities with his grandfather Herod the
Great. He understood Judaism, he was the first to be called king
by the Roman emperor since his grandfather, and he died a horrible
death. Modern scholars think Herod the Great died of chronic kidney
disease exacerbated by maggot-infected gangrene of the genitals. It's
been noticed that Agrippa I, the silver-bedecked king who died with
maggots in his gut, is the perfect illustration of a white-washed
tomb (Matthew 23:27). His external appearance, and actions, have
one appearance, while the reality of what's inside is awful.

This is in contrast to Barnabas and Paul in Acts 14:8–18. When
the people of Lystra declare Barnabas Zeus and Paul Hermes, the two
immediately tear their robes and stop the people from sacrificing
to them. Paul spends his ministry understanding his place before
God. Despite all his credentials as a faithful Jew, Paul considers
all his good works "rubbish" (Philippians 3:8). Only Christ matters.

The word for "struck" is the same used in Acts 12:7 when the angel
"struck" Peter. The angel struck Peter to wake him and rescue
him from prison. Now, the angel strikes Agrippa to afflict and
destroy him.  Context Summary Acts 12:20–23 describes some of
the details of the death of Herod Agrippa I. He was the first
true king since his grandfather, Herod the Great, and ruled over
nearly as much territory. He had an abnormally good relationship
with the Jewish leadership and was one of the few Roman rulers
of the area to persecute the church. But his favor with the Jews
evidently contributed to his pride. He accepted the glory due only
to God and died while his bowels were eaten by worms. Josephus,
an ancient historian, provides some details Scripture does not.