Ugh... I'm atheist / agnostic and haven't uttered a prayer in years, but this kind of meme aggravates me. Let me count the ways:

-- It's the exact same kind of virtue signalling you're complaining about. Prayers aren't working? Well, clearly an Internet meme will fix things right up!

-- It's rankly hypocritical. Have you ever, say, put a rainbow or French-flag-colored overlay on your Facebook image pic? Or maybe reposted some Occupy Democrat meme you found somewhere? Please articulate how your French flag image is any different than somebody posting 'thoughts and prayers.' Both are signaling that you are aware of an issue without actually doing anything about it.

Pivoting more into the San Bernardino context from which this meme arose:

-- It's blood dancing. There were people on site of the shooting asking for prayers at the same time the people offering them (on FB) were getting castigated by others posting this meme.

-- This meme is usually posted as part of a call to 'do something,' which usually makes me think the poster has about the same mentality and level of knowledge of the issue at hand as Helen Lovejoy (https://en.wikipedia.org/wiki/Think_of_the_children).

-- Said calls to 'do something' came in before any knowledge of what guns the shooters were using came in, how they were attained, or what said shooters ideological or political motivations are. Crying to 'do something' before you know if what you are proposing would have prevented this tells me you're ignorant; if you know that you don't know if it will be effective tells me you see this as an opportunity for naked politicization (see blood-dancing above).

So, while I agree that prayers, thoughts, FB overlays, re-posting of memes, and the rest of the dazzling array of virtue signalling possibilities are largely useless, using this meme is indulging in the so much more of the same. In other words, you're not doing your cause any favors.