What is the ruling on one who has killed thousands of Muslims, burned their mosques, insulted the Qur'an, and declared his enmity toward that which pleases Allah? And what is the ruling on his supporters, whether they be ignorant or learned?

These heinous acts vary. Some are oppression and corruption, some are disbelief, and some are judged according to their motive. Killing innocent Muslims is an injustice, and intending to insult the Qur'an is disbelief. As for burning and besieging mosques, if it is intended to insult the houses of Allah, it is disbelief. But if it is due to personal enmity or fighting its inhabitants, then it is not so. Al-Hajjaj did what he did to the Sacred House due to enmity with Ibn al-Zubayr, not intending to insult the House. Whoever supports an oppressor or approves of his action shares the same ruling as him, according to the Prophet, peace and blessings be upon him, who said: "If a sin is committed on earth, whoever witnesses it and dislikes it is like one who was absent from it, and whoever was absent from it and approved of it is like one who witnessed it." And his saying: "Whoever dislikes it has absolved himself, and whoever denounces it has saved himself, but whoever approves and follows..." It must be noted that ruling someone a disbeliever is not a light matter and must be governed by Sharia (definition) regulations.