The doctrine of the impeccability of Christ is an important teaching of the church and it is the basis of the illustration I've used explaining the OP title, so it is relevant for what I wished to show from my own experience. For those not familiar with the teaching, I suggest reading in the Systematic Theology of Robert L. Dabney, which you can read online:
https://grace-ebooks.com/library/Robert%20Dabney/RLD_Systematic%20Theology.pdfDo a 'Find on Page' for "impecc" and select the 4th occurence. Dabney's presentation on the impeccability of Christ is 4 pages starting on p886 and on page 890 he moves on to "Does Christ Medicate in Both Natures"?" which is important to read following the impeccability of Christ.
Over the years I began to notice that we as Calvinists, in our theology are averse to 'leaving the ends undone' and must understand and explain every difficult text. Lutherans I've found are willing to let a text mean what it says, even if it cannot be easily explained, and this is mentioned by the Lutheran David Kuske in his textbook on interpretation, "Biblical Interpretation, The Only Right Way" -
"John Calvin (d. 1564) followed many of the same principles of interpretation that Luther did. There was one major difference, however. When Scripture says something that is difficult or even impossible for human reason to grasp (e.g. predestination, the real presence in the Lord's Supper, the two natures of Christ), Luther insisted that what Scripture says must be what it means, even though it may not be able to be fully understood. Calvin, on the other hand, felt that any such matter should be interpreted in a way that the meaning of the words were comprehensible to human reason." page 152-153
The impeccability or peccability of Christ dictates how one views Heb. 4:15. Was it possible for Christ to sin, or was it impossible for Christ to sin. In the discussion, the peccability views says he could have sinned in his human nature or it would not have been a true temptation; viewed by the impeccability of Christ he could not have sinned. One brief proof for me is "No one, when tempted, should say, “I am being tempted by God”;
for God cannot be tempted by evil and he himself tempts no one. But one is tempted by one’s own desire, being lured and enticed by it; then, when that desire has conceived, it gives birth to sin, and that sin, when it is fully grown, gives birth to death." (Jas 1:13-15 NRSV)
John Gill in his Body of Divinity states in Book 5, Chap. 1 & 2 - "for
in Christ was no sin, lust, or corruptton to stir up" and "Perfect holiness and impeccability: it is called, "the holy Thing"; it is eminently and perfectly so; without original sin, or any actual transgression; it is not conscious of
any sin, never committed any, nor is it possible it should."
I therefore deny the possiblity of separating the Human from the Divine in the One Person, the Christ. In view of my belief, what am I to do with Mark 13:32, a favorite used by the Jehovah's Witnesses?
“But about that day or hour no one knows, neither the angels in heaven, nor the Son, but only the Father." (Mark 13:32 NRSV)
If I can't separate the Human from the Divine in Christ as to Heb. 4:15, how can I explain
to my human reason, this verse restricting the knowledge of Jesus Christ by restricting this to Christ's human nature apart from his Divinity? I choose to admit I do not have a certain answer to this? I prefer to leave such questions in the realm of the incomprehensibile nature of God and just let the verse mean what it says. In like manner, I deal with such passages as the proof text of Christ's divinity in Zech. 12:10 and a similar statement in 1 Cor. 2:8.
"And I will pour upon the house of David, and upon the inhabitants of Jerusalem, the spirit of grace and of supplication; and
they shall look unto me whom they have pierced; and they shall mourn for him, as one mourneth for his only son, and shall be in bitterness for him, as one that is in bitterness for his first-born." (Zech 12:10 ASV)
The text refers to [b]Yahweh being pierced, "me whom they have pierced"
[/b]
"...which none of the rulers of this world hath known: for had they known it, they would not have crucified the Lord of glory:" (1Cor 2:8 ASV)
Again, it is the Almighty God who is "the Lord of glory" that was crucified.
Rather than being dogmatic on theological theories, I prefer to stay with the following:
"Now these things, brethren, I have in a figure transferred to myself and Apollos for your sakes; that in us ye might
learn not to go beyond the things which are written; that no one of you be puffed up for the one against the other." (1Cor 4:6 ASV)
"O the depth of the riches and wisdom and knowledge of God! How unsearchable are his judgments and how inscrutable his ways! “For who has known the mind of the Lord? Or who has been his counselor?” (Rom 11:33-34, NRSV)
To see the debate, try an AI Search such as
www.phind.com and ask something like "Was the Son of God incarnate omniscient?" Bing's "copilot" is another AI search option as well as perplexity or you.com