The candidate must work for a religious organization in a traditionally religious function: such as liturgical workers, religious instructors, religious counselors, cantors, religious school teachers, workers in religious hospitals or religious health care facilities, missionaries, religious translators, or religious broadcasters.
The regulations exclude maintenance workers, not religious in nature, e.g. janitors, drivers, clerks, fund raisers, etc.
The sponsoring organization must meet the requirements of R-1 visa, meaning it has to be a tax-exempt organization under the Internal Revenue Service code.
the main distinction with the R-1 requirements is that the green card candidate must have at least two years of experience in a religious capacity. The experience does not have to be paid, it does not have to be full-time but it must be continuous (this is a very important criteria and must be properly documented).