Chréstos (Gr.) The early Gnostic form of Christ. It was used in the fifth century B.C. by Æschylus, Herodotus, and others. The Manteumata pythochresta, or the “oracles delivered by a Pythian god” “through a pythoness, are mentioned by the former (Choeph.901). Chréstian is not only “the seat of an oracle”, but an offering to, or for, the oracle.
Source: H.P.Blavatsky - The Theosophical Glossary
Chrestos (Gr.) The early gnostic term for Christ. This technical term was used in the fifth century B. C. by AEschylus, Herodotus and others. The Manteumata pythocresta, or the "Oracles delivered by a Pythian God" through a pythoness, are mentioned by the former (Cho. 901), and Pythocrestos is derived from chrao. Chresterion is not only "the test of an oracle," but an offering to, or for, the oracle. Chrestes is one who explains oracles, a "prophet and soothsayer," and Chresterios, one who serves an oracle or a God. The earliest Christian writer, Justin Martyr, in his first Apology, calls his co-religionists Chrestians. "It is only through ignorance that men call themselves Christians, instead of Chrestians," says Lactantius (lib. IV., cap. VII.). The terms Christ and Christians, spelt originally Chrest and Chrestians, were borrowed from the Temple vocabulary of the Pagans. Chrestos meant, in that vocabulary, "a disciple on probation," a candidate for hierophantship; who, when he had attained it, through Initiation, long trials and suffering, and had been anointed (i. e., "rubbed with oil," as Initiates and even Idols of the Gods were, as the last touch of ritualistic observance), was changed into Christos — the "purified" in esoteric or mystery language. In mystic symbology, indeed, Christes or Christos meant that the "way," the Path, was already trodden and the goal reached; when the fruits of the arduous labour, uniting the personality of evanescent clay with the indestructible INDIVIDUALITY, transformed it thereby into the immortal EGO. "At the end of the way stands the Christes," the Purifier; and the union once accomplished, the Chrestos, the "man of sorrow" became Christos himself. Paul, the Initiate, knew this, and meant this precisely, when he is made to say in bad translation, "I travail in birth again until Christ be formed in you" (Gal. iv., 19), the true rendering of which is, " . . . . until you form the Christos within yourselves." But the profane, who knew only that Chrestos was in some way connected with priest and prophet, and knew nothing about the hidden meaning of Christos, insisted, as did Lactantius and Justyn Martyr, on being called Chrestians instead of Christians. Every good individual, therefore, may find Christ in his "inner man," as Paul expresses it, (Ephes. iii., 16, 17) whether he be Jew, Mussulman, Hindu or Christian.
Source: H.P.Blavatsky - The Key to Theosophy, The theosophical glossary