New research from Allen Downey, a computer scientist at Olin College of Engineering in Massachusetts, shows a startling correlation between the rise of the Internet and the decline of religious affiliation in the United States.

According to MIT Technology Review, back in 1990 only eight percent of the U.S. population did not have a religious affiliation. Twenty years later in 2010 that number was up to 18 percent. That is a jump of 25 million people. Americans seem to be losing their religion, and from Downey’s research we may have an answer.

The data Downey looked at is from the General Social Survey, which according to MIT Technology Review is “a widely respected sociological survey carried out by the University of Chicago.” Since 1972, the survey has been measuring the population’s demographics and attitudes.

The approach to looking at the survey material was to see how socioeconomic status, education, religious upbringing and other factors correlated with the drop in religious affiliation. This is a good time to talk about the difference between correlation and causation. The data from the survey shows a relationship between these factors and decreased religious affiliation, but not direct causation.

Downey’s findings show that religious upbringing is the largest influence on religious affiliation. However a drop in religious upbringing starting in 1990, does not account for the entire drop of religious affiliation. According to the analysis, religious upbringing was important, but only explicated 25 percent of the drop.

Higher education at the college level also has a relationship with the drop in religiosity. But the study shows that rates of the college education from the 1980s to 2000s only went up a little under 10 percent (from 17.4 to 27.2). Statistically, this can only account for five percent of the drop.

The internet, if you can believe it, has a much higher correlation than college education. According to the study, Internet use went from near zero percent in the 1980s, to 53 percent of the population spending up to two hours a week online in the 2000s. MIT Technology Review reports:

“This increase closely matches the decrease in religious affiliation. In fact, Downey calculates that it can account for about 25 percent of the drop.” Twenty-five percent — the same percent correlation as religious upbringing. And while this is only a correlation (X might cause Y, Y might cause X, W and X might cause Y, etc.) and not a direct causation (X causes Y), Downy says, “Correlation does provide evidence in favor of causation, especially when we can eliminate alternative explanations or have reason to believe that they are less likely.”