What factors bear on the authenticity of Χριστοῦ in 1 John 1:7?

Question

The word “Christ” is absent in most modern translations of 1 John 1:7

But if we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus his Son cleanses us from all sin. (ESV)

But if we walk in the light, as he is in the light, we have fellowship one with another, and the blood of Jesus Christ his Son cleanseth us from all sin. (KJV)

There are 2 words in the Received Text (TR) not used in the Critical Text (NU):

ἐὰν δὲ ἐν τῷ φωτὶ περιπατῶμεν, ὡς αὐτός ἐστιν ἐν τῷ φωτὶ,κοινωνίαν ἔχομεν μετ᾽ ἀλλήλων, καὶ τὸ αἷμα Ἰησοῦ Χριστοῦ τοῦ υἱοῦαὐτοῦ καθαρίζει ἡμᾶς ἀπὸ πάσης ἁμαρτίας (TR)

ἐὰν ἐν τῷ φωτὶ περιπατῶμεν, ὡς αὐτός ἐστιν ἐν τῷ φωτί, κοινωνίαν ἔχομεν μετ’ ἀλλήλων, καὶ τὸ αἷμα Ἰησοῦ τοῦ υἱοῦ αὐτοῦ καθαρίζει ἡμᾶς ἀπὸ πάσης ἁμαρτίας. (NA 28)

My understanding is that primary difference between the Received and Majority Texts from the NU Text stems from the acceptance of the Alexandrian text type manuscripts as the best representation of the original text. Since "δὲ" and “Χριστοῦ” are missing from these manuscripts, they have been deleted from the text thought to be original.

What seems odd about this decision is that one point of the Epistle is that Jesus is the Christ:

Who is the liar but he who denies that Jesus is the Christ? (2:22a ESV)

Including “Christ” in verse 7 seems logical given this message, while removing it raises the question, what blood cleanses?

Does the blood of Jesus cleanse?
Does the blood of Jesus Christ cleanse?

It is easy to explain the change as a scribal addition of “Christ.” Yet it is difficult to see why the writer, trying to defend their position that Jesus is the Christ would forget to include it.

Question 1: in contrast to the "blood of Jesus Christ cleanses us from all sin", what is the significance of the "blood of Jesus cleanses is from all sin" in the context of this Epistle? Also are the 2 additions δὲ and Χριστοῦ related?

Alexandria was the location from which Gnostic and the Arian heresy originated. For me, that raises a concern over the fidelity of any manuscript (of the period) associated with Alexandria or the Alexandrian school which taught scribes.

Question 2: is it accurate to see Alexandrian text type manuscripts as originating, either directly from Alexandria or from the school(s) in Alexandria?

Question 3: if there is a connection between Alexandria and the Alexandrian text manuscripts, what evidence is there that the manuscripts of 1 John presumed to be the best representation of the original text were not influenced by Gnosticism and Arianism in Alexandria?

Answer 1

There are at least three variants of the passage you cite (according to the apparatus of the Nestle-Aland Greek-English New Testament, 11th ed.):

(a) και το αιμα ιησου του υιου αυτου ...
And the blood of Jesus His Son ...

(b) και το αιμα ιησου χριστου του υιου αυτου ...
And the blood of Jesus Christ His Son ...

(c) και το αιμα ιησου χριστου ...
And the blood of Jesus Christ ...

Variant (a), as you point out, is the one given in the Critical Text. It is found in the Sinaiticus (א) and Vaticanus (B) Codices. Both date from the 4th century. The text is also represented as such in certain Latin, Syriac, and Coptic versions.

Variant (b) is found in the 5th century Alexandrinus Codex (A) and is also the majority reading. The text is also represented as such in other Syriac and Coptic versions. It is also the text that has come down to and is in use in the Greek-speaking churches today (see text here).

Variant (c) appears only in a few manuscripts and is also quoted as such by Cassiodorus (6th c.)

With the exception of (c), which is obscure, both variants make reference to Jesus as the Son of God, with the appelation "Christ" omitted in some manuscripts. If, as you suggest, the variants which exclude the word "Christ" were somehow influenced by Arian interpretation, one would think that they would have also omitted the reference to Jesus as God's Son.

Furthermore, if certain scribes deliberatly removed the word "Christ" from this particular passage, one would expect them to have similarly removed other ocurrences. But this is not the case. The word also appears in the so-called "Byzantine text form" (i.e. Textus Receptus) in 1:3, 2:1, 3:22, 4:2, 4:3, 5:1, 5:6, etc. Consider, for example:

Who is he that overcometh the world, but he that believeth that Jesus is the Son of God? This is he that came by water and blood, even Jesus Christ (5:5-6, KJV)

There is no indication, at least in my reading of the Nestle-Aland apparatus, that the references to Jesus as the Son of God and as the Christ are missing in the Alexandrinus Codex.