Religion can heal, as the studies in your book show. It seems equally evident, though, that religion can kill, too.
Of course. Throughout history, personal faith and religious institutions have been a great force for good, motivating selfless behavior and compassion and magnificent works of service to others. At the same time, religious institutions and leaders have been sources of divisiveness and hate, and religious movements have existed throughout history which have targeted outsiders for destruction. Thousands of studies by now have shown that expressions of religious faith or spirituality are associated, on average, with all kinds of benefits for our well-being — less depression, less anxiety, even longevity in some studies. And sociologists and psychologists and economists and political scientists have documented the other ways that religion or faith has impacted humanity for the good.
But at the same time, so many people have been harmed by religion. Emotionally abused, disfellowshipped or rejected, unfairly judged, left feeling diminished rather than uplifted. It's hard to convince some people that religion is intrinsically a positive force when they experience themselves or their loved ones being abused or tortured or even killed in the name of religion. Honestly, religion isn't a single unitary thing, and it's not all good or all bad. It's better thought of as a domain or dimension of life -- a vessel that can be filled up with goodness that can nurture and comfort and even heal but can also be filled with sludge and sickness that can do vile things to people and ruin lives.