Believe was a musical event, honoring Master Chief Petty Officer John-117 for his service to the UNSC. It was performed on September 25, 2556 at the UNSC Symphony Hall, and performed by the UNSC Symphony Orchestra of the UNSCDP.
- "Believe" is one of two slogans for Halo 3, the other is "Finish the Fight".
- Believe was performed on September 25, the release date for Halo 3.
- The word "Believe" can be seen on the walls of New Mombasa buildings in Halo 3: ODST.