Abu Issa Mohammed ibn Harun al-Warraq was a 9th Century skeptical scholar and critic of Islam.
He was a mentor and friend of scholar Ibn al-Rawandi in whose work The Book of the Emerald he appears.
Some Muslim sources have described him as being a Muslim and others a Manichaean

Al-Warraq was skeptical of the existence of Allah because "He who orders his slave to do things that he knows him to be incapable of doing, then punishes him, is a fool." Warraq also doubted claims portraying Mohammed as a prophet