Final answer:
Roman Catholicism has the largest number of adherents in the U.S., outnumbering any single Protestant denomination such as Baptist, Methodist, or Pentecostal churches.
Step-by-step explanation:
The single Christian faith with the largest number of adherents in the U.S. is Roman Catholicism. Despite the numerous Protestant denominations such as Baptist, Methodist, and Pentecostal, Catholic followers outnumber any single one of these individual Protestant groups. It is important to note that while the Protestant religions, including Baptist, Methodist, and Pentecostal have significant numbers, the Catholic Church maintains a prevalent presence across the country. The map distribution of religious organizations reflects the high concentration of Baptist churches in the Southeast, which is part of the region known as the Bible Belt; however, this does not surpass the overall number of nationwide Catholic adherents.