A creed is the set of beliefs that defines a person's religion, and can therefore be used as a synonym for religion in general (e.g. 'Membership is open to people of all creeds').
In Christianity, the creed is a part of the service liturgy where the congregation recites a list of their beliefs. There are several different creeds, including the Apostles' Creed and the Nicene Creed, although all include the basic tenets of Christianity such as belief in God the Father, God the Son and the Holy Spirit.
Some Protestant denominations do not accept creeds as authoritative, holding to the doctrine of sola scriptura instead. As such, recitation of any kind of a standardized authoritative formula of belief is not part of the worship service. However, depending on which creed is being discussed, adherents may nevertheless accept it as an accurate summation of traditional Christian doctrine.