What is the meaning of Allah Almighty's saying, "Alif, Lam, Mim"?

Nothing has been authentically reported from the Prophet, may Allah bless him and grant him peace, regarding the meanings of the disconnected letters (al-Huroof al-Muqatta'ah). For this reason, commentators have differed concerning them. The most preponderant opinions are that they are among the manifestations of the Qur'an's miraculousness, and that Allah alone possesses knowledge of their meaning. Thus, they are among the 'mutashabih' (ambiguous verses) that Allah referred to in His statement: "And no one knows its true interpretation except Allah."