The afterlife was not something to look forward to during the Egyptian times. It was considered a very dangerous place to be because it was also known as the land full of dangers. This was why the dead brought the Book of the Dead to help fight off horrible things that would come in their way like snakes, fires and executioners, which would have scared a lot of people half to death!
People had to bring the Book of the Dead otherwise they probably wouldn't have had a very good chance of surviving in the underworld! The Book of the Dead contained magic spells that would help fight off dangerous creatures that came in there way, which would have been scary, in my opinion! Some of the creatures were snakes, fires and executioners, people that chop your head off :( The Book of the Dead was guaranteed to give you a safe passage through the underworld. 
