Now lets have my take into the topic:
Ali bin Abu-Talib (r.a.) said: "The Messenger of Allah called me and told me: 'You are alike with Jesus, Jews hated him till they slandered his mother, and Christians loved him till they put him in the position that is not for him.' With regard to me, two categories of people will be ruined, namely he who loves me too much and the love takes him away from rightfulness, and he who hates me too much and the hatred takes him away from rightfulness. Verily, I am not a prophet, and there is nothing revealed to me. But I work with the Book of Allah and the Sunnah of his Prophet () as much as I can. So whatever I have asked you in regard of obeying Allah, it is your duty to obey me whether you like it or not." [Ahmad]
Ali (r.a.) said: "With regard to me, two categories of people will be ruined, namely he who loves me too much and the love takes him away from rightfulness, and he who hates me too much and the hatred takes him away from rightfulness. The best man with regard to me is he who is on the middle course. So be with him and be with the great majority (of Muslims) because Allah's hand (of protection) is on keeping unity." [Nahjul Balagha, sermon 126 about the Kharijites]
In the that time, people who called them selves Muslims were three groups :
1- Kharijiteswho said that Ali was a disbeliever and they send Ibn Muljim to kill him and he did that. Then Nawasib like you who who love, respect and follow those of your ancestors who were open Nawasib and used to hate, curse, oppose and fight Ali bin Abi Talib [as]. The first extreme.
2 - Nuseries who deemed Ali bin Abi Talib [as] as God [Nauzobillah]. The second extreme.
3- Shias who said that he was infalleble Imam and Allah had chosen him for leading Muslims, based on textual proofs. The middle course.