Apart from direct charity, which does not require theism to operate in the first place, church services do not provide any measurable benefit to society. This wide latitude in the interpretation of their benefit leaves them open to abuse by church operators, who see tax exemption as a window to make easy income. Taxation would discourage this abuse from happening while directly benefiting society with more revenues.
"Churches, surely, have contributed to the success of America by encouraging virtue, but social science research has also shown that churches provide direct and indirect economic and social benefits to communities. Churches provide valuable contributions to communities in the areas of direct economic contributions, social services and community volunteering, education and civic skills training, and reduced levels of deviance."