The name is derived from the English word, which ultimately derives from the Latin “Creda,” meaning, “creed, belief.”
Creed was first used as a male name in 17th-century England, perhaps among the Puritans or perhaps in reference to the surname, which was common in Somerset and Cornwall, England.
There is a Norman church located in Cornwall known as St. Crida, Creed. St. Crida or St. Cride was the name of an elusive Cornish female saint, her church and hamlet being the only testament to her possible existence. The hamlet in which the Church is located is also known as Creed. Whether Crida is connected to a Cornish source or to the Latin Creda is unknown. However, I cannot find any sources indicating that Crida was ever used as a given name. In other sources, the above is suggested to be connected to another elusive Cornish saint known as St. Grada the Virgin, which in turn is connected to another medieval Church in Cornwall known as St Grada & Holy Cross Church, Grade in Grade, Cornwall. The latter was initially known as St. Cross Church in the 13th-century, then was later known as St. Grada, Virgin by the 14th-century. In any case, Creed itself is often listed as unisex name on most baby name websites, but it doesn’t appear to have been used as a female name until the 19th-century, and most records occur in the United States. It does often appear as a female middle name in 16th-century Cornish sources, but I cannot confirm if this was in reference to a family surname, perhaps that of the mother.
The name first appeared in the U.S. top 1000 in 1910, coming in as the 942nd most popular male name. It disappeared and re-entered the U.S. Top 1000 in 2016 as the 982nd most popular male name.
In the last 139 years, the name has yet to appear among the the U.S. top 1000 female names.
Sources
https://www.behindthename.com/name/creed/submitted
https://www.ssa.gov/oact/babynames/index.html
http://forebears.co.uk/surnames/creed
https://historicengland.org.uk/listing/the-list/list-entry/1141938
https://www.familysearch.org
https://en.wikipedia.org/wiki/St_Crida%27s_Church,_Creed