Islam was introduced and taught to the world – in its pure form by Prophet Muhammad. After his demise, the responsibility to carry out the mission of Islam was entrusted (through divine will) to the bloodline (progeny) of the Prophet.
Ahlul Bayt are collectively a group of divinely appointed individuals whom Allah has sent as guidance to mankind. They consist of the bloodline of Prophet Muhammad (the last and final messenger to mankind) – Lady Fatema (daughter of the Prophet) and the Twelve rightful successors (peach be upon them all) – the pure and chosen inheritors of the knowledge, character and personality of Muhammad through whom true Islam has survived.
In the tragic history of Islam, the rights of the Ahlul Bayt were usurped by corrupt individuals who illegally took their position as successors. That is how Islam got corrupted over time. True Islam has been and is constantly under attack – by both outsiders and insiders (it’s own corrupt followers). Allah has and will continue to preserve the truth which miraculously survives in a minority group through the guardianship of the Ahlul Bayt.
The Ahlul Bayt have been entrusted with the great Trust – delivery of truth and guidance to mankind. They are the fountain heads of knowledge, shelters (protectors, guardians) of His teachings, and strong forts protecting the Qur’an and it’s Message. They are the lofty citadels defending His Message. True Islam needed help and support to survive – Allah chose them and through them made Islam strong and powerful.