The Intended Audience is Anyone Who Reads John's Gospel
First, it should go without saying that there is a Jewish background to all Scripture, even epistles written primarily to a Gentile audience. It would be a fallacy then to assert that simply because of references to Jewish ideas that there is "primarily a Jewish audience" in mind.
Second, John chapter 1 makes many statements to set the stage for defining to the reader what "Christ" means, both to Jews and Gentiles (i.e. all people). Each group needed some educating, and John 1 begins that process. Thus, by the time of John 20:31, the reference there to Christ is intended to be understood in the context of how John has defined Christ throughout his work.
Yes, familiarity with the OT (whether LXX or not) is helpful, a Jewish understanding of Messiah/Christ is also helpful, but look at what chapter 1 reveals simply to anyone reading the text (all Scripture quotes from John 1 of the NASB; I have bolded all the defining "qualities" of "Christ" from this passage):
- The subject is One called the Word, who was both with God and was God (v.1) from the beginning (v.2).
- This Word caused all else to exist (v.3, 10)
- In this Word was life, which itself was light to men (v.4).
- The life (light) of this Word was testified of a man named John (the Baptist, v.6-8), for the purpose of people coming to believe (note the similarity of purpose between John the Baptist's coming, and John the apostle's reference in 20:31—belief).
- This Word/Light entered into the world (v.9-10).1
- Upon entering, the Word/Light came to a group that were "His own" (i.e. His own people) who did not as a group receive Him (v.11), yet some people did receive Him (v.12a), and this Word/Light had authority to grant authority for those so receiving to "become children of God" (v.12b), a type of birth that comes only by God (v.13).
- This Word uniquely incarnated into a man, and through such incarnation manifested glory (v.14), being higher than John the Baptist in importance (v.15), manifesting grace and truth (v.16-17)
- The man is identified as "Jesus Christ" (v.17)—Here is the first mention of Christ in John's gospel. It is used as part of the designation of this incarnated Word/Light Person. Thus, all that was stated of the Word/Light in v.1-16 defines "Christ" for the reader.
- This Christ has both "seen God" and "explained" (or "declared," KJV) God (v.18).
- John the Baptist, the earthly messenger of this Christ (v.23), denies being himself the Christ (v.19-20), nor the Prophet like unto Moses that was to come (v.21; cf. Dt 18:15), who the Jews, priests, Levites, and Pharisees (v.19, 24) expected to come (and expect to baptize when he does, v.25); but John asserts this one they seek (i.e. Christ) is among them (v.26).
- And John the Baptist points Him out the next day as Jesus, "the Lamb of God who takes away the sin of the world!" (v.29-30, v.36).
- This one John saw the Spirit descended upon (v.32), and it is He who will baptize with the Spirit (v.33), for He is "the Son of God" (v.34).
- "Christ," as defined by the chapter, is identified as "the Messiah" that the Jews sought (v.41), "of whom Moses in the Law and also the Prophets wrote" (v.45), and recognized by one as "the Son of God ... the King of Israel" (v.49), and also identified with "the Son of Man" (v.51).
There are Jewish aspects for sure, but also universal points as well. Indeed, as many hold, the promise of one to come from humanity to handle the problems of mankind came first to Adam and Eve (Gen 3:15), before the further revelation of His political and ethnic relation to Israel found in later OT Scriptures.
Your Specific Questions
- Does the use of the term χριστὸς itself suggest a Jewish audience?
- Can Carson’s argument be justified on a grammatical basis?
- If the grammar is correct, is this a firm argument for a Jewish audience?
The first I believe is answered in the negative based on the introduction of Christ in chapter 1, where the essentials of "Christ" are defined (essentials both to a Gentile and a Jew). The third I believe is then a mute point, since even if Carson's grammatical argument is justified, the conclusion then of a primarily Jewish audience based on an emphasis of the idea of Christ is fallacious.2 Regarding the justification of the second point, Wallace specifically addresses Carson's argument, and considers it invalid.3 The key points of his rejection there are:
- Wallace notes that Carson argues on the basis that "an articular noun takes priority over a proper name" (Christ is articular in Jn 20:31), which Wallace notes that Carson himself relies on E. V. N. Geotchius' grammatical work as support.4
- But the NT evidence is ambiguous with the rule of predicate nominatives as Wallace sets forth, which is that the subject is either the first noun in sentence order or in some cases the proper name taking priority over an articular noun even if the proper noun is not first in order.5 the support used by Geotchius/Carson's argument is based off citations of Act 5:42 (a verbless clause), 18:5, and 18:28 (both have the verb to be first,
εἶναι τὸν χριστὸν Ἰησοῦν), which do all have the articular noun as the subject, but in each of those cases Wallace points out that the articular noun is the first in word order (which does not match the Jn 20:31 passage order that has the subject even preceding the verb,
Ἰησοῦς ἐστιν ὁ χριστὸς ὁ υἱὸς τοῦ θεοῦ). So it is the word order that makes them the subject of those passages, not the articular noun being present. Wallace notes Act 11:20 is a missed case in point against Geotchius/Carson, where the message (again verbless,
τὸν κύριον Ἰησοῦν) is not "the Lord is Jesus" but "Jesus is the Lord" (translations generally omit any verbal idea, putting "the Lord Jesus" as a title, but that title is still itself asserting either one or the other of the ideas behind the verbal assertions).6
- As a third counter point, Wallace notes the same grammatical construction as Jn 20:31 is used in 1 John 2:22, 4:15, 5:1, and 5:5 (primarily 2:22 and 5:1 are parallel to the discussion about Christ, but for identifying grammatical subject, the other two are evidence as well). But Wallace contends that "the audience" of 1 John "seems clearly to be of a Gentile nature (cf. 5:21)."7 This is merely for Wallace to counter Carson's use of the grammar to support a Jewish audience for John's gospel, as the same grammar is found in a letter to Gentiles.
John chapter 1 defines for the reader who "Christ" is, and yes, He is identified with the one expected by the Jews, but also identified as God Himself, life and light, the one that takes care of the sin of all mankind (universal aspects). Chapter 1 points the reader back to the OT revelation to help one understand better who this Christ is, but also lays much ground for those unfamiliar with those writings to understand the rest of the Gospel message of John the apostle, so that anyone reading what has "been written" in his gospel "may believe that Jesus is the Christ, the Son of God; and that believing you may have life in His name" (Jn 20:31). It could also be said that the emphasis on it being written down points to the intended audience being the reader (whoever that is).
John considers his gospel to largely be a self-contained message (1) defining the important essence of who Christ is, (2) defending that Jesus is this Christ, all for (3) the purpose that people believe it. This makes anyone who reads it his intended audience (though the Jews would have the advantage [or stumbling block, as was often the case] of knowing what was written of Messiah previously).
1 I personally believe v.9-12 refer to the manifestations of pre-incarnate Christ, including the message of the Word/Light of Scripture itself prior to His incarnation, since v.14 clearly refers to the incarnation. So v.9 is saying that "every man" who encountered the Light of the Word (i.e. Scripture or a direct visit from God) was enlightened by that encounter, but "His own" (mankind in general, but Israel specifically) largely did not receive Him (being in disbelief, rebellion, etc.), though some did (v.10), including some Gentiles in the OT.
2 Note Carson's conclusion that you quoted:
the writer conceives of his purpose . . . less as the answer to the
question Who is Jesus? than to the question Who is the messiah?
I would agree, but John has defined in chapter 1 the important aspects of the Messiah (while also pointing readers to investigate further if needed from the OT testimony).
3Daniel B. Wallace, Greek Grammar Beyond the Basics: Exegetical Syntax of the New Testament (Zondervan, 1999), 46.
6Though Wallace does not elaborate, I believe the essence of his using Acts 11:20 as counter parallel to the Acts 5:42 (also verbless), 18:5, and 18:28 constructions is that it would not be valid to assert "the Lord [Yahweh] is Jesus," as Yahweh existed prior to Jesus being born as a man, but it would be right to assert "Jesus is the Lord [Yahweh]," because Jesus (the man) is the incarnation of Yahweh. So Wallace's argument here depends on a theological understanding.
7Wallace, 46. His use of 1 Jn 5:21 as proof of Gentiles is using the fact that at this point in history, the Jews had largely ceased from idolatry being their sin (it was a Gentile sin at that time). Whether one considers Wallace's point that 1 John was written to Gentiles or not will determine the force of this part of his argument agaisnt Carson.