Complex sentence: Amaq News Agency released a statement claiming the attacker was a soldier of ISIS who had "struck one of the most famous nightclubs where the Christians celebrate their apostate holiday", and described Turkey as a "protector of the cross".
Split into simpler sentences: Amaq News Agency released a statement claiming the attacker was a soldier of ISIS. ISIS stated that the attacker had "struck one of the most famous nightclubs where the Christians celebrate their apostate holiday", and described Turkey as a "protector of the cross".