The NIV footnote to Jude 1 alerted me to a great example of the challenges of the dative case. The second part of the salutation reads, “To those who have been called, who are loved in God the Father (τοῖς ἐν θεῷ πατρὶ ἠγαπημένοις) and kept for Jesus Christ (Ἰησοῦ Χριστῷ τετηρημένοις).” The NIV goes with “in” for ἐν, although its meaning is not immediately apparent, and it goes with “for” for the dative Ἰησοῦ Χριστῷ. The footnote reds, “Or by; or in.”
You can see other translations struggling with this rather ambiguous construction. The ESV footnotes “for” with, “Or by” The CSB uses “by” and “for” without footnotes. The NET has, “to those who are called, wrapped in the love of God the Father and kept for Jesus Christ.” The NLT expansively has, “I am writing to all who have been called by God the Father, who loves you and keeps you safe in the care of Jesus Christ.” (If this is confusing to you, note that they have not kept the two participles ἠγαπημένοις and τετηρημένοις modifying “called” as do other translations.)
But what does it mean to be loved “in God”? Moo says it refers to “the context in which we experience love.” Love “is the product of our ... being in fellowship with God.”
What does it mean to be “kept for Jesus Christ”? The dative allows for either Jesus being the one who keeps us, or that Jesus is the one for whom we are kept. Moo again comments, “God throughout this life exercises his power on behalf of Christians to preserve them spiritually intact until the coming of Jesus Christ in glory.”
Whatever you do this verse, my suggestion is not to base any doctrine on it. The dative is just too vague to be useful here.
The irony of this is that prepositions were introduced into the Greek language as a way to bring specificity to cases. However, in so many situations now, the preposition is as flexible as the case.
On a totally different vein, we sang an old song in church today that says, “I dare not trust the sweetest frame, but wholly lean on Jesus’ name.” Does anyone have any idea what “frame” means? I don’t.

Comments
Frame
From etymonline.com, this etymology seems to apply best, I think:
From 1660s in the meaning "particular state" (as in Frame of mind, 1711).
The Sweetest Frame
“I dare not trust the sweetest frame, but wholly lean on Jesus’ name” from a hymn by Edward Mote in 1863. Just as a frame encloses, encompasses, and holds together a picture or painting, so our “sweetest frame” is everything that gives shape and beauty to our present life—family, home, health, possessions, achievements and security. We may rightly value these things, but we dare not make them the foundation of our confidence, for every earthly frame is temporary. The only foundation on which we can wholly lean is Jesus and His unfailing righteousness.
The Sweetest Frame
“I dare not trust the sweetest frame, but wholly lean on Jesus’ name” from a hymn by Edward Mote in 1863. Just as a frame encloses, encompasses, and holds together a picture or painting, so our “sweetest frame” is everything that gives shape and beauty to our present life—family, home, health, possessions, achievements and security. We may rightly value these things, but we dare not make them the foundation of our confidence, for every earthly frame is temporary. The only foundation on which we can wholly lean is Jesus and His unfailing righteousness.
Use of "frame" as object of trust
I have always sung this phrase, thinking of it as "physical frame", meaning the flesh, carnal nature of self or fear of man (others). Christ alone has the writer's trust.
I may be wrong. Perhaps the writer found this the best scansion and rhyme fit for his intention,
Frame
I'm going to toss out what it implies to me.
I am working backwards from what the implied
meaning seems to mean to me. I speak from the
allure of the addictive process.
There is a scripture: there is a way which seems right to
man, but it leads to death (did not take time to look up
exact wording). I think the way many wrong decisions
are made: It feels right (as in comfortable, or 'sweet')
Frame here seems to be a shortening for effect that
sometimes happens in poetic settings. I would
suspect that the author is taking poetic license and
shorting a phrase like 'frame of mine'; 'frame of thought'
or simply the way that people frame their perspectives
to suit what is comfortable (or sweet) for them.
Possible connection: The Sweetest Frame
Edward Mote (London) wrote "The Solid Rock" in 1834. It's possible he was reading Ralph Erskine's (Scotland) sermons. Here's from a 1821 edition, "Sermons and Practical Works", pg 328, I wonder if maybe he picked up the idea of a "sweet frame" from this exposition. It certainly clarifies - that the "sweet frame" is the vessel, the structure, the feelings and acts of salvation - but Christ is the only source.
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"The man that is dead to the law, can, in some measure, put a difference betwixt Christ and a frame: whereas, he that is alive to the law, can never distinguish between Christ in duty, and a frame in duty. I suppose this is a hard question, How shall we know the difference betwixt Christ in duty, and a frame in duty. I will answer, in a word, The man that hath only a frame in duty and not Christ in it, he is only pleased with his frame, his tears, his enlargements; he makes that his righteousness; he is content with that, and exalted with that; and now thinks all is well: "
"but he that hath Christ in duty, and not a frame only, he is ready to cry, O I would have Christ! tears will not do the turn; my own heart hath deceived me a thousand times; I find my tears do not wash me, my frame does not sanctify me: this flowing of affection may be but a natural thing; it will not do; it is Christ I want; nothing but his blood can wash me: nothing but this blood can pacify his conscience; nothing but some views of Christ can give him solid quiet"
"A sweet frame may indeed be the chariot, in which Christ may ride towards the soul; but the gospel-believer is not so much taken up with the glorious King that rides in it."
"Law-Death, Gospel-Life: or, the Death of Legal Righteousness the Life of Gospel Holiness" Ralph Erskine
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Possible connection: The Sweetest Frame
edit the last part of the quote, significant typo!
"the gospel-believer is not so much taken up with the chariot as with the glorious King that rides in it."
Instrumental case?
Dear Bill,
Thank you very much for your interesting considerations on the greek NT language, which I read with pleasure. I am not a greek scholar, but studied latin many years back and delight myself in learning NT greek.
This said, a simple question: a very natural way of reading the passage you analyzed would be to analyze Ἰησοῦ Χριστῷ as instrumental case, as we indeed are kept 'through' or 'by' Jesus Christ?
What is the main reason you would reject this analysis?
Thank you very much and best regards from Switzerland