Chemical engineer Mubarak Bala, 29, says he is being drugged and held against his will in a psychiatric ward in Kano.
Bala alerted people to his plight with tweets from a smuggled phone, saying his father beat him up, sedated him and that he recovered consciousness in the hospital.
Bala describes his father as an Islamic leader who "can't afford to have a non-Muslim family member, so he declared me insane."
Lawyer Muhammad Bello Shehu says Bala's father said he committed his son for safety as he could be lynched for denying God exists.