Deutéronome 31:18

But I will indeed remove My Shekinah from them at that time, until they have dwindled away, to receive the punishment of their sins for all the evil they have wrought, because they turned themselves after the idols of the nations.

I shall utterly conceal In the sense that if they call Me, I will not answer. The analogy is to a man who cannot be seen, so no one knows what he is going to do. The Hebrew language repeats a verb to express emphasis or intensification, as the grammarians well know.

they turned to This is the greatest of all evils, as I have explained [comment on 28: 14].

AND I WILL SURELY HIDE MY FACE IN THAT DAY. The meaning thereof is that [He will hide His face] on a different occasion [for it was already stated in Verse 17, and I will hide My face from them]. Since the Israelites already reflected in their hearts that they sinned against G-d, and that these evils came upon them because their G-d was not among them, it would have been fitting — according to the exceeding mercies of G-d — that He help them and rescue them because they had already denied the idols. This is similar to what is stated, Behold, I will enter into judgment with thee, because thou sayest: ‘I have not sinned,’ [indicating that the very denial of wrongdoing is a grievous sin, but here the admission of sin should have caused G-d to help them]. Therefore he [Moses] states that, because of the great evil that they did in trusting idols, He will again hide His face from them — not like the first hiding of His face when He hid the face of His mercies and many evils and troubles came upon them — but that only the face of redemption will be hidden and they will abide by the promise of the face of His mercies. [This is the promise of] And yet for all that, when they are in the land of their enemies, I will not reject them, neither will I abhor them etc. [They will not be shown the face of redemption] until they add to the aforementioned regret real confession and perfect repentance, as is stated above, and thou shalt return unto the Eternal thy G-d etc.

ואנכי הסתר אסתיר פני מהם, not as they thought that I was no longer in their midst; wherever they are My presence is with them, as our sages said in Megillah 29 “wherever the Jewish people have been exiled G’d’s presence accompanies them. However, it does not manifest itself by saving them from their oppressor.”

על כל הרעה אשר עשה, Israel had done harm to itself, not G’d.

כי פנה אל אלוהים אחרים, while being beset by all of their problems, instead of turning to Me in prayer, supplication and remorse, they chose to pray to idols instead.

ואנכי הסתר אסתיר, “and I will hide Myself even further;” our sages derive from this line that the Purim story i.e. the scroll of Esther and Mordechai are of Biblical authority [Esther’s real name having been Hadass, Ed.] i.e. that even during periods of exile when we do not feel the presence of G–d around us, He nonetheless watches over us and intervenes in our fates decisively when we are under attack. [Although His name does not even appear in that scroll, Haman did not succeed in killing a single Jew. Ed.]