I'm fairly sure there is a study somewhere (if not, there ought to be) showing a tremendous decrease in the number of Christians fed to the lions in Roman areas, after the Roman emperors converted to Christianity.
Clearly there is a correlation between Christianity and not feeding people to the lions, for sport, right?
Absolutely!..BUT..well, not exactly...after converting to Christianity, the Roman rulers stopped feeding Christians to the lions. They kept on feeding pagans to the lions for a couple more centuries, until the fall of the Roman Empire. Seems to me that the "Christian" values of the converted Romans didn't end people being lion chow in their arenas, it only changed who they chose as their victim pool.
In science, as in any investigation into the cause of a fault or problem, we look at everything involved, but we only change one thing at a time. When we change only one thing, and get the same/similar result that we had in the beginning, we have a reasonable certainty that one thing wasn't the cause of the fault. Then we change a different thing, and repeat that process until we hit on the one thing (or combination of things) that does give us a different result than we had in the beginning.
Society never changes just ONE thing at a time. Multiple things, up to millions of things change, and any study claiming ONE thing, was the cause, WITHOUT considering equally ALL the other things that changed is flawed to the point of uselessness for any serious rational purpose. It's nothing more than opinion, paid for by someone, and usually reflecting the views of the people paying for the study, or the people doing the study, and not a cause and effect backed with facts, only facts that have a casual relationship, or as the popular phrase today goes, a "correlation".