Emotions Misguide
After the death of the Prophet (صلي الله عليه وسلم), many tribes apostated from Islam. Some stopped paying zakaah (poor-due), and some tribe leaders claimed prophethood. Many of the common people at that time lacked education. The emotional charge of the situation swept up many of the Muslims.
Protect yourself. If you allow the river of emotion to sweep you up, in a lot of cases, it will misguide you towards the wrong direction.