I have just joined this forum, and I am jumping in to comment on some topics dealing with Islam.
One of the problems (from a non-Muslim point of view) with Islam is that it combines religion and politics. It’s similar to the idea of the Pope and the Papal States in the 15th-16th centuries. The caliph was not just a religious leader, he was the head of the government. The two were inseparable in early Islam.
So Hussain was both a religious and a political figure. This is unlike Jesus, who was only religious (although some opponents accused him of trying to be a king of the Jews). The story of Hussain lacks the self-sacrificial aspect of Jesus and his death. Hussain didn’t march out against the Umayyads with the object of becoming a martyr–he expected others to rally to his cause, and he expected to win. He was badly mistaken! Also, Jesus was sacrificing himself for a purpose: the salvation of mankind. Hussain’s purpose was simply that he believed he, as a grandson of Ali, was a better candidate to be caliph. There is no grander purpose behind his death. So there are some superficial similarities, but the differences are more substantial.
Hasantas is correct, mourning is forbidden in Islam. That doesn’t mean people don’t mourn, however. Islam belong to the “It was meant to be” philosophy of history, and to mourn would theoretically be challenging God’s will. But of course people do mourn.
You shouldn’t underestimate the example of Jesus in the Muslim mind of the time though. There MAY have been conscious or subconscious modeling of Hussain and his suffering on Jesus and his suffering. At the very least, Hussain was (and is) considered a martyr, again, with possible conscious or sub-conscious modeling on Christian martyrs. Certainly their are similarities, although you can’t trace actual connections as far as I know.
Hadith are not generally used as historical sources by Western scholars. There is the issue of how many were genuine memories that were passed down and how many were forgeries. Both Muslim and Western scholars agree on this, but each has its own methods of deciding what is genuine.