What is the "divine anger"?
According to Jewish scholar Ziony Zevit, Jewish interpreters are unsure what the expression a great wrath came upon Israel actually means in the Masoretic Text (footnote in the Oxford Jewish Study Bible).
The Septuagint translates the older proto-Hebrew text as great regret [μετάμελος] came in Israel. The word only occurs in the Septuagint. Elsewhere (with Brenton's translation):
When a just man dies he leaves regret [i.e. "will be missed"]: but the destruction of the ungodly is speedy, and causes
3 Maccabees 2:22–24
Shaking him to and fro as a reed is shaken with the wind, he cast him upon the pavement, powerless, with limbs paralyzed ... When in
of time he had come to himself, this severe check caused no
repentance within him, but he departed with bitter threatenings.
The Latin Vulgate also originates in a text older than the Masoretic, being derived from Jerome's original Latin translation of some proto-Hebrew. It reads the underlying word as something that is in Israel and not against Israel:
et facta est indignatio magna in Israel
and there was great indignation in Israel (Douay-Rheims)
All of the above points to an interpretation NOT that the king of Moab eventually prevailed - helped by an "outburst of divine anger" - against Israel, after sacrificing his son; but RATHER, I think, that the king of Moab was regretful at/in Israel because everything that he tried - including his filial sacrifice - had failed.
Is there really another god out there that we have only just heard of?
I am not sure it is correct to say that Scripture never admits the existence of [other] gods (small "g"). Although there are numerous admonitions not to worship or honor other gods (e.g. Exodus 20:3, 34:14; Deuteronomy 5:7), I do not believe there is any place in the Old Testament that states that no other "gods" exist.
As to who these other "gods" are, the Septuagint reading of Psalm 96 (95 in the LXX) tells us:
The gods of the nations are demons.
- Psalm 95:5 LXX
If so, shouldn't an omnipotent and omniscient God allow His people to triumph?
As I plead above, I do not believe that the Israelites were defeated in the end, but even if it were the case, God's omnipotence and omniscience does not preclude His allowing His people to fail. If so, then one should argue why the Fall (capital "F") was allowed to occur.
God chastens those whom He loves (Proverbs 3:12; also Hebrews 12:6). In the Old Testament, there are several examples, I think, of where the Israelite's enemies were permitted to prevail because of some disobedience on their part. Examples of this would include the defeats by the Amorites (Numbers 14) and Ai (Joshua 7), Egypt (2 Chronicles 12), and Egypt (2 Chronicles 12). Of the last, Scripture says:
2 Chronicles 12:1 (KJV 1900)
And it came to pass, when Rehoboam had established the kingdom, and had strengthened himself, he forsook the law of the LORD, and all
Israel with him.
2 Chronicles 12:5
Then came Shemaiah the prophet to Rehoboam, and to the princes of Judah, that were gathered together to Jerusalem because of Shishak,
and said unto them, Thus saith the LORD, Ye have forsaken me, and
therefore have I also left you in the hand of Shishak.
After this defeat at the hands of Chemosh, is Elisha's prophecy now proven a lie, thus rendering him a false prophet?
A skewed reading of 2 Kings 3 would certainly make this seem so, as argued, for example, in the exegesis presented in this particular posting of the blog, "Politely Rejecting Jesus". (link expired)
I don't think that's the case, though, when the Scripture is really studied in the full context available to us.