Sometimes I see all Christian bookstores as a gimmick to make some money. But I'm not always so cynical.
I read how the WWJD thing got started. Naturally, somebody decided to run with it and make some money. But it really was just a reminder.
And I would agree with your Pastor if I were sinless. But, wretch that I am, I need a reminder of who I am now and then.
Shalom.