I have heard someone say that Sunni's are Kafir because they do Takfir of Abu Taleb AS and this is on the basis that calling a Muslim a Kafir makes one a Kafir. How can I respond?
1. Sunnis are Muslims like us and it is completely wrong to claim that they are Kafirs.
2. Sunni are following different sects e.g. Hanafi, Shafi'ee, Maliki, Hanbali, Salati, Wahabi, Sufi, Barelwi, Deobandi etc.
There are also many Sunni sub sects. All of them Muslims even those extreme groups who claim that Shia are Kafir. We believe that those who call us Kaafir are Muslims but misguided.
3. Abu Talib is a great believer in Islam and protector of the Prophet (SAWA) and this fact is been admitted by mass majority of Sunni scholars. Small minority among Sunni Muslims claim that Abu Talib was non Muslim because of the enmity against imam Ali (AS).
4. Many Sunni scholars have written books about Abu Talib and his great status in Islam e.g. Ahmad Zaini Dahlan the Imam of the Haram of Makkah.
Wassalam..