Religious Workers
Some religious travel such as religious conventions and conferences can be done on a tourist (B1/B2) visa, but for all types of religious workers (paid or unpaid), the R visa is required. This category requires a petition that must be filed in the United States by your religious sponsor.
If you are intending to preach or do any other form of religious work, please review the Department of State’s guidance on Temporary Religious Worker Visas prior to submitting your application.