What about “The Da Vinci Code”?

well i was reading a book by a scoffer, and he says that one reason that jesus wasn't alive was that there was no record of him in the area. he claims that the levites and secret society's took the story of horus and changed the names and dates to jesus. he claiims that writers like philo were there and never wrote of jesus. there is a few others too, but that one is good for now. and how could jesus be born of original sin if his mother wasn't. if she wasn't born with immaculate conception, she must have some original sin in her. i would like to know how to counter this mans arguement. thank you. jason