The 12th Imam (atfs)

Imam Sadiq (asws) in a lengthy narration:

ثم انى أخبرك ان الدين واصل الدين هو رجل وذلك الرجل هو اليقين وهو الايمان وهو امام أمته وأهل زمانه فمن عرف عرف الله ومن أنكره أنكر الله ودينه ومن جهله جهل الله ودينه وحدوده وشرايعه بغير ذلك الامام كذلك جرى بان معرفة الرجال دين الله

"Then I hereby inform you that the Religion and the foundation of Religion,  is a man, and that man itself is certainty (yaqeen), and He is faith, and He is the Imam (asws) of His community and the Imam of the people of His time. So the one who recognizes Him has recognized Allah (swt), and the one who denies Him has denied Allah (swt), and His religion, and the one who is ignorant of Him is ignorant of Allah (swt) and His Religion, and His Limits, and His laws. Hence it happens to be that the Recognition of that man is the religion of Allah (swt)" 

[Source: Basair al-Darajaat, Pg, 539]