This is a summary of why we need to follow the Prophet (Sawa) and the Ahlulbayt (As):
"O Allah, introduce me to Yourself; because if You do not introduce me to Yourself then I would not know your messenger.
O Allah, introduce me to Your Messenger, because if You do not introduce me to Your Messenger then I would not know Your Proof.
O Allah, introduce me to Your Proof, because if You do not introduce me to Your Proof then I would be mislead about my religion."
Reference: Al-Sadooq, Kamal al-deen wa Itmam al-Neama, p 342. Al-Kulaini, al-Kafi, 377/1.