I have personally seen tangible effects of prayer in my own life. When I hear about a tragedy such as this, prayer is really the only immediate thing that I feel I can do to help those involved in any way. Sure, there are more long-term ways to contribute, provide aid, and help to bring about change that might prevent this type of thing from happening (whatever your beliefs are), but in the raw immediate moments after something like this happens, I think prayer is a very meaningful way for many people to feel like they are "there" for the people affected. It's fine if you don't subscribe to those beliefs, but don't suggest that it's not meaningful for anyone else. I would wager that there are multiple people who are grieving in El Paso right now that would absolutely say that it is meaningful to them to know that there are people all over the country/world praying for them.

Since this thread is already way out of the TOS bounds, I'll go farther. Lack of faith, in my opinion, is one of the main reasons this is such a problem unique to the United States, as you point out. Our country has made faith and traditional values/morals taboo, which has led to the dissolution of the family unit and has also created a large section of the population that is searching for something they can't find, and they end up feeling isolated, forgotten, downtrodden, etc. Some of those people end up doing horrific things like this.

I'm not going to participate in a gun control debate here. But there is much more contributing to this issue than access to guns, and I think gun control advocates that ignore that fact are disengenuous. We as a country need to figure out how to resolve the cause of the problem, not try to simply prevent a possible symptom of it. There is a personal identity/moral/mental health crisis going on that needs a lot more attention, but the farther our country moves away from its original values and morals, the harder it's going to be to fix it.

All just my opinion, of course.