faith (n.)
https://www.etymonline.com/word/faith
mid-13c., faith, feith, fei, fai "faithfulness to a trust or promise;
loyalty to a person; honesty, truthfulness,"from Anglo-French and Old French feid, foi "faith, belief, trust, con-
fidence; pledge" (11c.),from Latin fides "trust, faith, confidence, reliance, credence, belief,"
from root of fidere "to trust,"
from PIE root *bheidh- "to trust, confide, persuade."
From early 14c. as "assent of the mind to the truth of a statement for
which there is incomplete evidence," especially "belief in religious
matters" (matched with hope and charity).Since mid-14c. in reference to the Christian church or religion;
from late 14c. in reference to any religious persuasion.
And faith is neither the submission of the reason, nor is it the accep-
tance, simply and absolutely upon testimony, of what reason cannot reach.Faith is: the being able to cleave to a power of goodness appealing to
our higher and real self, not to our lower and apparent self.
[Matthew Arnold, "Literature & Dogma," 1873]
From late 14c. as "confidence in a person or thing with reference to
truthfulness or reliability,"
also "fidelity of one spouse to another."
Also in Middle English "a sworn oath,"
hence its frequent use in Middle English oaths and asseverations
(par ma fay, mid-13c.; bi my fay, c. 1300).
belief (n.)
https://www.etymonline.com/word/belief?ref=etymonline_crossreference
late 12c., bileave, "confidence reposed in a person or thing; faith
in a religion,"replacing Old English geleafa "belief, faith,"
from West Germanic *ga-laubon "to hold dear, esteem, trust"
(source also of Old Saxon gilobo,
Middle Dutch gelove,
Old High German giloubo,
German Glaube),from *galaub- "dear, esteemed,"
from intensive prefix *ga- + PIE root *leubh- "to care, desire, love."The prefix was altered on analogy of the verb believe.
The distinction of the final consonant from that of believe developed
15c.
The be-, which is not a natural prefix of nouns, was prefixed on the
analogy of the vb. (where it is naturally an intensive) .... [OED]
Meaning "conviction of the truth of a proposition or alleged fact with-
out knowledge" is by 1530s;
it is also "sometimes used to include the absolute conviction or cer-
tainty which accompanies knowledge" [Century Dictionary].From c. 1200 as "a creed, essential doctrines of a religion or church,
things held to be true as a matter of religious doctrine;"
the general sense of "That which is believed" is by 1714.Belief meant "trust in God,"
while faith meant "loyalty to a person based on promise or duty"
(a sense preserved in keep one's faith, in good (or bad) faith,
and in common usage of faithful, faithless,
which contain no notion of divinity).
But faith, as cognate of Latin fides, took on the religious sense
beginning in 14c. translations,
and belief had by 16c. become limited to "mental acceptance of some-
thing as true,"
from the religious use in the sense of "things held to be true as
a matter of religious doctrine."
belief と faith との異同について。
初めは 神の信仰は ビリーフがその意味を担っていたが のち（１４ｃ）
になって フェイスのほうがそれに取って代わったとか。
ラテン語の fides の翻訳にあたって 同じ語源の フェイスのほうが使わ
れるようになったのだと。
☆ そのほか 分かったこととしては：
・ belief ∽ German Glaube
from *galaub- "dear, esteemed,"
from intensive prefix *ga- + PIE（ ProtoIndoEuropean ） root *leubh-
"to care, desire, love."
・ faith:
https://www.etymonline.com/word/faith?ref=etymonline_crossreference
from Latin fides "trust, faith, confidence, reliance, credence, belief,"
from root of fidere "to trust,"
from PIE root *bheidh- "to trust, confide, persuade."
☆ しかし 気に入らない点があります。
個人にとっての《信仰――信教・良心の自由というときの〈信じる〉――》こと
であるのに《宗教的な用法・意味（religious use ?）》としか言っていない。
真実（ to be true ）として捉えるのは オシヘとして（as a matter of
religious doctrine ?）だと言っています。
つまり ここから日本語における通念としての《〈キリスト教〉という教》で表
現することが 来ているのでしょうか。
