The World Values Survey is an association of social scientists from around the world that gather data on human values, political and social life, as well as a host of other social statistics. Using the WVS data, the following figures show that the belief in God, in the Unites States has declined since the 1980s. The data also show an interesting correlation between the belief in God and the Violent Crime Rate.
The second figure, using WVS data and violent crime rate data from the FBI, shows the correlation between belief in god and crime. As can be seen, the correlation between the violent crime rate and the American belief in god, is high, with a correlation coefficient of 0.84, i.e., as belief in God decreases, so to does the violent crime rate. Obviously, there are many factors contributing to the declining crime rate, but perhaps the belief in God, or lack thereof, is a related variable.
1)The WVS collected survey data on the belief in God in from their surveys in 1981, 1990, 1995, 1999, 2005, an 2010. The data for 2013-2016, comes from a Gallup survey, which surveyed the same question, "Do you believe in God".
2) The spurious correlation figure used the WVS and Gallup belief data from 201, 2013, 2011, 1999, 1995 and 1981, and the associated violent crime rate.