In this series of posts I will put forward the following set of ideas. They are not entirely new or original, but I think that there is a strong philological case to support them.
In southern Britain in the fifth century there was a significant Latin-speaking Christian British population. This is evidenced by pre-550 Latin loanwords in Old English and in particular by Christian terminology. The loanwords are most likely to be due to this population adopting Old English as their first language. This may be why there is also an important group of religious terms coined in Old English rather than borrowed from Latin. And it also explains why there are virtually no British loanwords in Old English.
IV. Summary of the previous posts.
It was argued that eight Christian Latin loanwords were borrowed between the settlement and the Augustinian mission
All eight words are very unlikely on a priori grounds to have been borrowed into the language of the Anglo-Saxons prior to the settlement. In some cases there are additional grounds for ruling this out. They are also all likely on linguistic and especially phonological grounds to have entered primitive Old English from some form of late Latin before about 550. And, as we have argued above, the conditions for the entry of such words into the vocabulary of a community are:
(i) regular, relatively peaceful contact between a Christian group using the source language (either a settled community or a mission), and the group using the borrowing language
(ii) a practical use for the terminology among speakers of the borrowing language.
The implication of this is that there were Latin-speaking Christian communities in southern Britain in the fifth century that were encountered by at least some Anglo-Saxon settlers. My hypothesis is that these late Latin Christian vocabulary items came into Old English in Britain, during and after the initial settlement period, well before the Augustinian mission, and in a situation of regular social contact between a Germanic-speaking settler community and a resident Latin-speaking community.
Archaeological evidence points to a degree of peaceful coexistence between Anglo-Saxon and British communities at various periods. I suggest that it was in such a context that the earliest Latin loanwords entered Old English, and that the reason why there are few Celtic loanwords in Old English is that the ordinary language of significant parts of southern lowland Britain was late Latin.
Mechanisms for the adoption of loanwords
There are two situations in which Language A adopts loanwords from Language B:
1) A community of speakers of Language A perceive certain words in Language B as useful or necessary: this may be because they have entered a new geographical area containing flora, fauna, customs, etc., not found in their original context, or because the culture expressed by Language B is perceived as prestigious. In this case the loanwords are often regarded as alien for a long time, and certainly as extraneous add-ons rather than core items.
2) A community of speakers of Language B adopt Language A as their main language, and carry over words from Language B (via intermediate code-switching). In this case the transfer of the loanwords is organic, in that they simply remain in the active use of the community during and after the period of language use shift.
Are there parallels for the acquisition of loanwords from language B in language A when a B-speaking community shifts to using language A? The answer is definitely yes. In Rome, the early Christian community was Greek-speaking. When the community shifted to Latin, a number of Greek religious terms (as well as other terms, of course) entered Latin, such as abbas, diaconus, ecclesia, episcopus, pascha, pentecoste, presbyter, etc. Similarly, the west European Jewish community in the early Middle Ages shifted language several times, from Italic late Latin to Old French to Middle High German, and in doing so carried Romance-derived words such as the etymons of benshn, davnen, and leynen into Yiddish.
Either of the above mechanisms could have brought Latin loanwords into Old English in the period between the settlement and the Augustinian mission.
Some of the Latin vocabulary that entered Old English at this time was Christian. It seems less likely to me that the settlers would have embraced Christianity, though it is not entirely impossible. Given the archaeological evidence for material acculturation of the native population to the incoming one, it seems much more likely that some or all British communities, pagan and Christian, shifted their language to Old English.
On this hypothesis I suggest that in the course of adopting Old English a resident Latin-speaking Christian community carried over many Latin words, including Christian ones. These loanwords then spread to the rest of the Old English speaking population. The Christian Latin loanwords were then available for use after the majority of the population adopted Christianity from 597 onwards.