The nullifiers of Islam are many. The gravest of these include Shirk (associating others with Allah in His Divinity or worship) by invoking and seeking relief from the dead, slaughtering animals and making vows at their graves, and other acts of worship practiced at graves as a means of drawing closer to the dead to ask them to fulfill their needs. (Part No. 1; Page No. 405) Acts that also invalidate one's Islam include learning and teaching sorcery, claiming knowledge of the Ghayb (the Unseen), believing that ruling by other than Allah's laws is permissible, abandoning Salah (prayer) deliberately, mocking Islam, insulting Allah and His Messenger and ridiculing the Qur'an and Sunnah.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.