This is an example of the conservatism, even archaism of Celtic Christianity.
From the en.wikipedia.org
Quien as a plural form survives as an archaism that is now considered non-standard.
From the en.wikipedia.org
Today it is regarded as an archaism and replaced by the handheld calculator.
From the en.wikipedia.org
The multiple unbalances in the ME are the obvious consequences of political archaism.
From the economist.com
Weigh's choice of idioms can sometimes seem at odds with the archaism of the situation.
From the guardian.co.uk
Richelieu did his work, too, in a time of witch burning and archaism.
From the time.com
He had been too long in post-Soviet Ukraine, where this archaism survives among the village old timers.
From the economist.com
It is this sense of archaism that makes the city so unique.
From the edition.cnn.com
Arnheiter, who became her new skipper at Christmas time 1966, was another sort of updated archaism.
From the time.com
More examples
The use of an archaic expression
(archaist) a person who archaizes
(archaist) antiquary: an expert or collector of antiquities
(archaistic) imitative of an archaic style or manner; "archaistic writing"
In language, an archaism (from the Ancientu00A0Greek: u1F00u03C1u03C7u03B1u03CAu03BAu03CCu03C2, archau00EFku00F3s, 'old-fashioned, antiquated', ultimately u1F00u03C1u03C7u03B1u1FD6u03BFu03C2, archau00EEos, 'from the beginning, ancient') is the use of a form of speech or writing that is no longer current or that is current only within a few special contexts...
Using obsolete or archaic words when current alternatives are available.
The deliberate use of obsolete words, grammar or expressions. This may be done because of the nature of the subject matter, to create a particular mood (for example, solemnity) or simply to help a poem rhyme or scan.
Old or outdated words or syntax which are intentionally used for effect.
A name which is antiquated in style or meaning (cf. Anachronism). For example, Clabber Girl baking powder recalls an earlier time.