Is it correct that the companion Wahb Al-Kalbi, who was murdered with Imam Al-Husain (a.) in Karbala, was not a Muslim and died as a christian?
Muhammad Baqir Al-Majlisi writes:
رأيت حديثا أن وهب هذا كان نصرانيا فأسلم هو وأمه على يدي الحسين
,,I discovered a tradition, that Wahb was a Nazarene, whereupon he became a Muslim, while his mother was standing in front of Al-Husain (a.).” [Bihar-ul-Anwar of Al-Majlisi, Volume 45 Page 17]
ثم برز من بعده وهب بن عبد الله بن حباب الكلبي وقد كانت معه أمه يومئذ فقالت: قم يا بني فانصر ابن بنت رسول الله، فقال: أفعل يا أماه ولا اقصر فبرز
,,Then Wahb Ibn Abdillah Ibn Habbab Al-Kalbi got up and on that day his mother was with him. She said: ,,Get up, O my son and help the son of the daughter of the Messenger of God!” Whereupon he said: ,,I will do it, o mother, and I will not remain inactive!” Then he arose.” [Bihar-ul-Anwar of Al-Majlisi, Volume 45 Page 16]
There is no reason to deny Islam to Wahb and his mother.