Much of Coptic literature is translated from Greek. In addition, Manichaean texts are presumably at least in part translated from Syriac; recent excavations of a Manichaean settlement at ancient Kellis, modern Ismant el-Kharab, in the Dakhla Oasis have unearthed bilingual documents for the first time providing hard evidence of this relation between Syriac and Coptic, in addition to many other interesting finds.
To the extent that it is translated, Coptic literature is less original and creative than it could have been. Then, again, translation Coptic is not as extensive as one might assume. If one excludes Biblical and related texts, a fair amount of what remains consists of original compositions, but even these original compositions exhibit a certain relation with work originally written in Greek. A large part of Coptic literature consists of countless homilies attributed to Greek-writing church fathers such as Athanasius of Alexandria and Cyril of Alexandria. There is no doubt, however, that these church fathers did not author the texts in question, and that the texts are original Coptic compositions. Their purport is much more popular in register than anything the authors in question ever wrote in Greek. On the other hand, it is not clear to what extent the Coptic homilies transmit, in strongly diluted form, titbits of exposition written by the author to whom the text is attributed or by any other church father for that matter. The outlines of theological thinking in Christian Egypt must have originated with great teachers of the church such as Athanasius. Some of their teachings presumably trickled down to popular homilies written in Coptic, but there is no evidence for the precise nature or the successive stages of this process. Clearly, the need was for homilies that could be read in church on Sunday and understood by a largely illiterate audience. Ancient sermons presumably came about in much the same way as those in modern times. Preachers draw on all kinds of direct and indirect sources of inspiration to compose them.
Translating Greek into Coptic requires proficiency in both languages. Such dual proficiency must have been rare. Although Greek was the language of a minority, this minority constituted the ruling class. There must have been little practical necessity for Greek speakers, typically city-dwellers, to learn the native Egyptian idiom spoken by most of the rural population. By contrast, studying Greek must have been seen as an instrument of upward mobility by many ambitious native speakers of Egyptian. In sum, there was more incentive for Coptic speakers to learn Greek than for Greek speakers to learn Coptic, except for the specific aim of translating Greek into Coptic.
Translating Greek into Coptic presupposes a near perfect knowledge of both. By contrast, in learning Greek for the purpose of social advancement, speakers of Coptic probably learned Greek to varying degrees of perfection. Coptic speakers with a far less than perfect knowledge of Greek must have been common. One piece of evidence in favor of this assumption is a unique fragment in which a Greek version and a Coptic version of a work attributed to Shenoute, the most prolific Coptic author, stand side by side (Depuydt 1989). The Coptic version seems perfectly idiomatic whereas the Greek is linguistically deficient in certain ways. What is more, the shortcomings of the Greek can in part be explained as a failed attempt to translate constructions unique to Coptic into Greek. Also, the Coptic text of a Bible passage is that of the Coptic Bible, whereas the Greek text is not that of the standard Greek Bible but rather an attempt at translation from the Coptic. The conclusion is obvious: Shenoute learned Greek, as one might have expected, but less than perfectly so.