This is the one text that Catholic, Eastern Orthodox, Oriental Orthodox, Anglican, Lutheran and a great many other churches all say. It is sung at the Eucharist in the Byzantine and Roman rites, professed at baptism in the East, and set to music more often than any other Christian text. If the atlas needed one document to stand for the doctrinal common ground of Christianity, this would be it.
Its history is oddly obscure for a document so central. It is associated with the Council of Constantinople in 381, which the emperor Theodosius called to settle the Arian question for good, but the creed is not quoted as that council's creed in any surviving source until the Council of Chalcedon read it into the record seventy years later. Scholars have argued that it was adapted at Constantinople from an existing baptismal creed rather than composed there. Nobody can settle it, and the atlas records the dispute rather than choosing.
What the text does is clear enough. It keeps the decisive Nicene word, of one being with the Father, and then does for the Holy Spirit what Nicaea had not done, calling him Lord and giver of life, proceeding from the Father, worshipped and glorified together with the Father and the Son. It stops short of applying homoousios to the Spirit, which is a deliberate restraint, and it adds the clauses on the church, one baptism and the resurrection that give the creed its liturgical shape.