Vice's Motherboard investigation (November 2020) revealed that Muslim Pro sold granular location data of its users to X-Mode Social, a data broker that supplied data to US military contractors and intelligence agencies. X-Mode also provided data to the IRS, Customs and Border Protection, and private intelligence firms. Location data from a prayer app reveals mosque attendance patterns, daily prayer routines, Ramadan observance, and -- most fundamentally -- that the user is Muslim. This data was sold to military contractors in a country that had recently implemented a travel ban targeting Muslim-majority countries. Muslim Pro initially denied selling data, then confirmed the X-Mode relationship and stated it had been terminated. The app designed to help 100 million Muslims practice their faith was simultaneously feeding their location data to the US military. The prayer app knew when you prayed. The military knew where.

Mozilla's Privacy Not Included project (2022) rated Pray.com among the worst apps for privacy across all categories -- not just prayer apps, but all apps reviewed. Mozilla found Pray.com collects an enormous amount of personal data and shares it widely. Prayer requests -- which users submit as personal petitions to God -- contain some of the most intimate disclosures humans make: prayers about cancer diagnoses, addiction struggles, marital infidelity, suicidal thoughts, financial ruin, children's illnesses. Pray.com's privacy practices treat these spiritual confessions as data points. The app shares data with Facebook and advertising networks. Terms allow sharing with "ministry partners" -- a category broad enough to include marketing and fundraising organisations. A person's prayer about their child's illness, submitted in faith, becomes a data point that flows through advertising infrastructure. The confession booth has an advertising SDK.

Hallow has raised over $100 million in venture capital. The app collects prayer habits, meditation frequency, which saints and devotions users engage with, and spiritual wellness data. This creates intimate profiles of users' religious lives — data that in many countries throughout history has been used for persecution. Hallow's privacy policy allows sharing data with third-party analytics and advertising partners.