"I am not a Mormon..."
hehehe
"why does Hitchens think Romney needs to answer for the entire Mormon faith? "
He was born a mormon and has held leadership positions in the church. Hitchens asks that he explain how that will impact a possible presidency, given the innumerable bizzare beliefs of mormonism.
"Why does he need to answer for Joseph Smith?"
He DOES need to "answer for" JS, because JS created the entire religion--including writing ALL the key doctrinal texts of the religion (except for the bible which was much downplayed in the early church). Mormonism IS Joesph Smith.
"Why should he have to answer for any anti-black racism?"
Because he was a member and had leadership roles in the church during that time. Because Mormonism at that time was the ONLY, relatively major, established religion that had racism AS PART OF ITS DOCTRINE! Rmoney needs to explain why he choose to belong to a church that went so far beyond any other church at the time to OFFICIALLY embrace racism as part of its religious teaching.