Just like anyone giving their info to MS or Amazon or an online banking service. Or even forming a business partnership with a friend believing they won't stab you in the back (continuing the Zuckerberg reference), or getting married on the faith your spouse isn't going to cheat on you. A great many decisions we make are made on faith in the integrity of the people we interact with.They are using "faith" in the sense of choosing to believe something without having supporting evidence to back up that belief. In this case, they are saying that the people who have given Sony their personal information had a belief that their information would be properly secured by Sony despite not having evidence that this would be the case...
If this database was created before PSNHack, there'd be no reason to doubt Sony's security. And TBH there's good reason to put one's faith in Sony's security now as they've been actively, publicly addressing it, whereas other companies people share personal information with remain a private unknown. The reason for questioning Sony's security at this point, IMO, is because it's obvious the hackers are targeting them specifically - it's not so much Sony's security one has to worry about, but these hacker chumps!...and in fact there being lots of evidence to the contrary.