1. Revelation 9:11 (ESV)
  2. Exposition

Why does John provide the name in two languages?

Revelation 9:11 (ESV)

11 They have as king over them the angel of the bottomless pit. His name in Hebrew is Abaddon, and in Greek he is called Apollyon.

John himself was a Jew and would surely wish all fellow Jews to know the Saviour and so escape the pain of hell. He also works among Greek‑speaking people in an effort to bring the gospel to them. The seven churches of Asia Minor were all Greek‑speaking. John would have this horrible summation of hell’s captain be widely known.