Sesa 'Refumee's heretic faction (Earth-2042)

"Our Prophets are false! Open your eyes, my brothers! They would use the faith of our forefathers to bring ruin to us all!"

- Sesa 'Refumee

A heretic faction led by Sesa 'Refumee broke away from the Confederacy of Independent Systems shortly after the Battle of Installation 04. Denouncing the religion of the Covenant, the Confederacy's biggest military supplier, they came to be regarded as heretics and were considered a substantial threat to the Covenant. The Hierarchs sent Arbiter Thel 'Vadamee to eliminate the secessionists before their message could spread and undermine the public faith in the Great Journey.

Source

 * https://www.halopedia.org/Sesa_%27Refumee%27s_heretic_faction