1) Abu Jahl and Abu Lahab and Abu Talib were from the same family that Rasoolullah SallAllahu alaihi wasallam was from, infact, they were His uncles. So what difference does it make? should we respect them? Islam teaches us " The most respectable amongst you is the one who is the more pious". Being Syed is not some reason to respect someone. If Allah doesn't bless one, a Syed like "Waris Shah" writes a useless novel like Heer Ranjha, and if it's Allah's blessings, a son of Hindu "Ahmed Ali Lahori" writes the commentary of the Qur'an. So who is the more respectable? Ask your friend, "If a prostitute is Syed, and there's a person with Jewish or Hindu father, but he himself is a pious Muslim, who is better? A prostitute or a Pious Muslim?" 2) It's the sunnah of Rasoolulllah SallAllahu alaihi wasallam that he used to fast in Ashura, as a matter of fact , when he was wasting on 10th of Muharram, some people told him that Jews also fast on this day, so Rasoolullah SallAllahu alaihi wasallam said "Oh, so if I remain alive next year, I'll fast two days ( i.e. , either 9th+10th or 10th+11th). Ask that shia "Was the deen completed in the time of Nabi SallAllahu alaihi wasallam or not?" if he says "yes", then ask him how can something that happened AFTER the Prophet SallAllahu alaihi wasallam be rendered haraam, especially something HE did himself? Secondly, ask him if the people killing Hussain Radhi Allahu anh were wearing clothes or not? If they were, then the shia should walk around naked. 3) Ask him what "Shia" means, If you don't know, "Shia" means group or sect or party. Sunni or Ahlus Sunnah means people who follow the path ( of Rasoolullah sallAllahu alaihi wasallam and His Companions [ May Allah be pleased with them ] ). How can a bunch of people who like "divide" themselves as their name itself calls them a "Group" be right? These are just a few points that you can pose in front of them.