The two portions clearly refer to
non-Israelites, as distinct from those who had joined fully with the nation.
I suppose vv14-16 should be read as insisting that, given one law for all, the non-Israelite would have to comply with the entire law and first be circumcised, in order to bring an acceptable offering. Calvin, and many others, believe this is the case. I am open to an argument that it could refer to a foreigner's offering of "token" devotion, or a "fearful" tribute.
V14 refers a) to the "sojourning stranger," which description runs the gamut of non-Israelites in the land; and b) one who is simply, literally, "among you," and I think the ESV quoted fails to give a good sense for the Hebrew, because it seems to separate a "permanent resident" from the previous category. In fact, the second category would go the opposite way--it refers to any non-Israelite who might (in someone's mind)
not be covered by the "sojourning stranger" description. No, but anyone AT ALL; the last phrase incorporates the least intentional, shortest staying person imaginable.
The offerings contemplated in the first vv of Num.15 seem to be primarily voluntary vows and freewill offerings. They should be viewed as a species of the "peace" offering, Lev.7:11ff. For the Israelite it would doubtless be thus connected to the rest of his religious life. For him, this sort of offering was of whole cloth with the rest of his covenant identity.
But for the non-Israelite, the
uncircumcised, these could not be properly construed as "peace offerings." Yet, perhaps the outsider was permitted to offer such token acknowledgement of "the God of Israel." Though not willing, for whatever reason, to take up the covenant privileges and responsibilities; still their public, quasi-formal recognition of the reign of Jehovah--to whatever degree it went--was accepted. We might compare this service to the paying of a tribute to a human king of a land not the traveler's home. There's a "politeness" to that gesture, which might even hold the seeds of even higher respect. "You seem to have a decent king (or God); I wish mine from back home (or where I came from) was half as worthy."
This understanding is reflected through the existence of the "court of the Gentiles" in Herod's Temple. "In Herod’s temple the outer court was marked off from the inner by “the middle wall of partition” (to mesoitoichon tou phragmou, Eph.2:15), beyond which a Gentile could not go. In this outer court was a house of prayer for the Gentiles (Mk.11:17)," A.T. Robertson. The same author on Act.21:28,
And moreover also he brought Greeks also into the temple (eti te kai Hellēnas eisēgagen eis to hieron). Note the three particles (eti te kai), and (te) still more (eti) also or even (kai). Worse than his teaching (didaskōn) is his dreadful deed: he actually brought (eisēgagen, second aorist active indicative of eisagō). This he had a right to do if they only went into the court of the Gentiles. But these Jews mean to imply that Paul had brought Greeks beyond this court into the court of Israel. An inscription was found by Clermont-Ganneau in Greek built into the walls of a mosque on the Via Dolorosa that was on the wall dividing the court of Israel from the court of the Gentiles. Death was the penalty to any Gentile who crossed over into the Court of Israel (The Athenaeum, July, 1871).
We are reminded from the Gospel accounts and Acts of the many Gentiles, passing through the Jewish lands, or curiously visiting Jerusalem, particularly at the feast-days, e.g. Jn.12:20ff (it is not possible to determine by John's use of the name "Greeks" what levels, possibly various, of devotion this grouping included); cf. Act.2:11. They were not all present there as worshipful, circumcised proselytes; though some would have been, and others were "God-fearers," as Cornelius, Act.10:22; and 13:16,26; who believed in the God of Israel, but who were more akin to "sojourning strangers." It's false, I believe, to interpret the "sojourning stranger" as a true proselyte.
According to Lev.22:25, no animal offering was acceptable that had been gotten from a foreigner/stranger (nekar). This could be a clear statement that precludes any non-Israelite offering. But, if the distinction holds observed in Steve's post above, between types of strangers, then not necessarily. Assuming they were permitted to make any sort of offering or donation, it had to have been procured by them from an Israelite. And of course, as with any offering, it had to be passed to the priest.
So, to sum up--the simplest way to understand this rule is to recognize that the "ONE rule or odinance"
included whatever prior conditions were necessary to make a "sojourning stranger's" person--and thus his offering--acceptable.
Conversely, a particular kind of sincere expression of fear or respect or honor to the God of Israel, presented by a stranger, might have found acceptance provided it met the same strict standards of cleanness and perfection as a covenant-member's. Scripture bears witness that God at times accepted very imperfectly offered worship, consider 2Ki.5:17-19; or 2Chr.30:17-20. Job 42:8 refers to offering and prayer, offered by a mediator, in behalf of others who's understanding of God is deeply flawed, even ignorant.
Finally, consider 2Chr.6:32-33 "Likewise, when a foreigner, who is not of your people Israel, comes from a far country for the sake of your great name and your mighty hand and your outstretched arm,
when he comes and prays toward this house, hear from heaven your dwelling place and do according to all for which the foreigner calls to you, in order that all the peoples of the earth may know your name and fear you, as do your people Israel, and that they may know that this house that I have built is called by your name." Material offerings ordinarily came with prayers from the ancients. It's how things were done.
In the final portion of Num.15 quoted, vv22-26, the mediation is clearly being offered for ALL PARTIES in the land, anyone who had the least worry of divine displeasure. Rest assured, God was propitiated for even the anxious stranger. And the final part, vv27-29, bridges the matter of unintentional sin and intentional. No one is supposed to fear unappeasable wrath and retribution who does not wilfully defy the law.