Eisegesis refers to interpreting a text by reading into it one's own ideas, or other ideas foreign to the text itself. Some apologists continue in a futile attempt to do that with Coptic John 1:1c.
For example, it is claimed that the indefinite ou.noute of Coptic John 1:1c should be translated as 'the one and only God,' because the indefinite article denotes unity, not 'a god.' As a "proof," 1 Corinthians 8:6 and Ephesians 4:6 are quoted, where ou.noute n.ouwt is usually rendered as "one God."
But that is erroneous eisegesis. It is a blatant attempt to read philosophical dogma into Coptic grammar. The Coptic indefinite article ou does not of itself 'denote unity.' It simply means "a" when bound with a common or count Coptic noun like noute, "god." The Coptic text of the New Testament contains hundreds of examples that prove this. (For example, see Coptic Acts 28:6, where the anarthrous Greek theos is rendered by ou.noute in Sahidic (Sahidica) and ou.nouti in the Coptic Bohairic version. Horner and Greek-based English versions including the KJV render this as "a god.")
Further, it is not the Coptic indefinite article ou that means "one," but the bound idiom ou______n.ouwt. This idiom literally means "a single, an only," and is used in Coptic to denote "one," adjectivally: "one god," "one man," "one spirit," etc. (For example, see Coptic Romans 5:12; 1 Corinthians 6:16, 17)
Therefore, ou.noute n.ouwt simply means "one god." It is the context, not the grammar, of 1 Corinthians 8:6 and Ephesians 4:6 that mandates the translation "one God" because the specific and definite reference in those verses is p.eiwt, "the Father," whom the Lord Jesus identifies as p.noute m.me m.mauaa.F , "the true God alone" (John 17:3 Horner), "the only true God."
Neither the grammar nor meaning of Coptic 1 Corinthians 8:6 or Ephesians 4:6 is the same as Coptic John 1:1c, so those verses cannot be used to exegete Coptic John 1:1c. Whereas ou.noute n.ouwt means a single god, i.e, "one god" or "one God" (in context, with reference to the Father), the fact remains that ou.noute means "a god." It does not mean some philosophical unity that calls for translating it as 'the one and only God.'
It would be far more honest to read Coptic John 1:1c for what it says, instead of trying to import foreign concepts into it.
And what Coptic John 1:1c clearly says is "the Word was a god." Or, if you prefer, "the Word was divine." But definitely not, "the Word was God."