Kids afraid of monsters under the bed? Don't explain to them that monsters aren't real! Instead dress them up in gaudy religious iconography and give them a pillow "shield" with which to defend themselves!
I can't help but be reminded of a scene in The Animatrix (The Second Renaissance, Part 2) where soldiers in a trench are preparing to fight the Machines, and an evangelist on TV is imploring them to "Put on your spiritual armor". Shortly thereafter they're all incinerated, blown up, or torn to pieces in the battle.
Speaking of incinerated, I also have some safety concerns regarding these pajamas. Looking at the banner at the top it appears that the entire page is smoldering. That *can't* be good!
My personal opinion is that ninja pajamas would be much more effective. After all, a monster can't eat what he can't see, right?