My question is whether calling Ali "Imam Ali" is a shibboleth that reveals that someone is a Shiite or not. I know the basic historical-political and doctrinal differences, including the imamate and the Shia belief that Ali was to be the temporal and spiritual leader of the Islamic community after the death of Muhammad. I assumed, then, that only Shiites would refer to him as "Imam Ali" and that Sunnis would just call him "Ali" or maybe "Caliph Ali." However, today I heard a non-Shiite scholar referring to him as Imam Ali, hence my question. Do non-Shia call him Imam Ali, too? When I search for "Imam Ali" online it seems that all the results are from Shia sources. Thank you in advance.
It is possible, but you can not be sure just because of it Ali ibn Abi Talib was an Imam for Sunnis as well:
- Caliphate is الإمامة الكبرى the caliph is the great Imam. Ali was one of the four rightly guided caliph.
- Leader in congregational prayer is called Imam, Ali lead prayers.
- Foremost experts in a field of knowledge (like fiqh or hadith) are called Imam. Ali was Imam in this sense as well.
As "Imam" in Arabic also means leader it is fine -from this perspective- to call 'Ali ibn Abi Talib an "imam".
What's the literal meanings of the word "Imam"?,
What is the reason for interpreting word Imam to book in Quran?
and What is an Imam, is he simply the leader of the jamaat?).
However when sunni's usually call him imam they don't give him the same attributes such as infallibility which shi'a give him. But they say it out of respect for his leadership in different matters be it Arabic language, fiqh or eloquence etc..
Being a non-Shiite, all I can say is that we consider Hazrat Ali(RA) our Imam too, although we don't usually emphasize on it, as we consider the Holy Prophet (SAW) to be the one and only true Leader.