The Ahlul-Bait are the Godly ones of the Family of the Holy Prophet Muhammad (PBUH&HP) whom the Muslim World as a whole unanimously acknowledges as the Pure Personalities and hold them as INFALLIBLE Holy ones PURIFIED By God Himself. The Almighty Allah has bestowed His trust on the Prophet Muhammad (The descendants of Muhammad, Peace Be Upon Them), who are the Strongholds of His Commandments. From where they are expounded and interpreted, they are The Fountain Heads of Knowledge Created by Him, Shelters for His Teachings, Forts for Heavenly Books, And lofty Citadels to defend His Religion. Islam needed help and support, By them Allah made Islam strong and powerful. Regarding the claim, Holy Quran says:

“When they had been patient and had conviction in Our signs, We appointed amongst them imams to guide [the people] by Our command”(32:24).

And:

“It is He who made the stars for you, so that you may be guided by them in the darkness of land and sea. We have certainly elaborated the signs for a people who have knowledge (6:97).

Ahlul-Bayt: Firmly Ground in Knowledge:

“It is He who has sent down to you the Book. Parts of it are definitive verses, which are the mother of the Book, while others are metaphorical. As for those in whose hearts is deviance, they pursue what is metaphorical in it, courting temptation, and seeking its interpretation. But no one knows its interpretation except Allah and those firmly grounded in knowledge; they say, ‘We believe in it; all of it is from our Lord.’ And none takes admonition except those who possess intellect”.(3:7).

And:

“Indeed, it is [present as] manifest signs in the breasts of those who have been given knowledge, and none contests Our signs except wrongdoers” (29:49).

The Blessed Ones:

“Guide us on the straight path– the path of those whom You have blessed — such as have not incurred Your wrath, nor are astray”(1:6&7).

 

Source: al-shia.org