International Day of Prayer for the Persecuted Church
The International Day of Prayer for the Persecuted Church (often abbreviated as IDOP) is an observance within the Christian calendar in which congregations pray for Christians who are persecuted for their faith. It falls on the first Sunday of November, within the liturgical period of Allhallowtide, which is dedicated to remembering the martyrs and saints of Christianity.
Source: Wikipedia — International Day of Prayer for the Persecuted Church (CC BY-SA 4.0)