There are parts of the bible that are highly pornographic, and if the Police arrested anyone over handing it out there would be an immediate backlash from it. Written speech is what has the most protection. Music is censored for profanity, and not for content otherwise "Caress me Down" would be banned for a highly graphic description of sex. It's played fairly regularly on one music station in Conservative Idaho so sex isn't as big of a deal when dealing with Music. None of the art galleries have been burned for having full nudes, or depictions of Roman debauchery. Last I checked minors were allowed in, and there has been no issue with the Police. However, things like Hustler and Playboy would cause an issue. The intent and market for Porn is sexual gratification, and where we draw the line with that has more to do with the culturally accepted age of consent. If you think that the US position on Porn is strange just go take a Hustler down to the Red Light districts in Japan. Most US porn is illegal in countries like Japan that somehow are able to accept much more extreme porn culturally, but show too much of one thing or another and it's illegal for even adults.