The freedom of religion and belief is enshrined in the core human rights treaties.
The U.S. State Department International Religious Freedom Reports are qualitative but have been coded by the Association of Religion Data Archives as part of their Religious Freedom Index.
Freedom House includes freedom of expression and belief as one of the metrics in their annual country reports.
Pew Research Center has been tracking data on religious restrictions in nearly 200 countries and territories since 2007. Their Global Restrictions on Religion data is updated periodically.
The Religion and State project at Bar Ilan University in Israel examines government religion policy and gauges the government support, restrictions, and discrimination against religious minorities.