Recent arrests of Muslim Cyber Army (MCA) members by the National Police’s cybercrime unit have shed light on the group’s network and its operations online, raising concerns about potentially rising sectarian sentiment, particularly in the lead up to the 2019 elections.

Last week, the national cyberpolice uncovered a syndicate called the Family MCA, which allegedly started the wildfire by spreading provocative information, from the rise of the Indonesia Communist Party (PKI) to persecutions of ulema, through various social media platforms.

Until Wednesday, the police had arrested six people from different areas in Indonesia, who were believed to be the brains behind the Family MCA group. Muhammad Luth, 40, was arrested in Tanjung Priok, North Jakarta, while Riski Surya Dharma, 35, in Pangkal Pinang, Bangka Belitung. Ramdani Saputra, 39, was arrested in Bali; Yuspiadin...