Fāsiq
Fāsiq is an Arabic term referring to someone who violates Islamic law.
As a Fāsiq is considered unreliable, his testimony is not accepted in Islamic courts. The terms Fāsiq and Fisq are sometime rendered as "impious", "venial sinner", or "depraved".
Origin
Fāsiq is derived from the term Fisq, "breaking the agreement" or "to leave or go out of."
In Islam the term Fāsiq describes a violator of Islamic laws, and sometimes can be associated with Kufr (disbelief).
Theological debate
=> The jurist Wāsil ibn Ata (700-748 CE) submitted that a Fāsiq remained a member of Muslim society, so retained rights to life and property though he could not hold a religious position.
=> This opinion set him at odds with Muʿtazilite jurists who considered a Fāsiq to be a Munāfiq (hypocrite), and the Khārijites who considered the Fāsiq a Kāfir.
=> To the Khārijites "faith without works" was worthless, so one who professed Islam yet sinned was Fāsiq, and thus a Kāfir.
Applications
Amongst the terms uses in geopolitics, in the period leading up to the 1979 Iranian Revolution, Ayatollah Khomeini described both the Shah of Iran and Saddam Hussein as Fāsiq.
In Shia discourse usually the Sunnis are called Fāsiqs – those who refused to follow the Purified Family of the Prophet Muhammad (ﷺ) (Ahl al-Bayt) – but nonetheless call themselves Muslims.