Do some people go to church because they have nothing more exciting to do? Jonathan Gruber (MIT) and Daniel Hungerman (Notre Dame) study the impact that eliminating "blue laws" has on church attendance. Blue laws limit the types of businesses that may operate on Sundays, often prohibiting retail activity. Get rid of a blue law, and you can go shopping on Sunday morning instead of attending church.
When a state repeals a blue law, does church attendance decrease? Yes. Also, church donations and spending also decrease, and there is an increase in drinking and drug use among the initially religious people who were affected by the blue laws. These results were recently published in the Quarterly Journal of Economics.
Link to the paper