For the children of Israel walked forty years in the wilderness, until all the nation, even the men of war who came forth out of Egypt, were consumed, because they didn't listen to the voice of Yahweh: to whom Yahweh swore that he wouldn't let them see the land which Yahweh swore to their fathers that he would give us, a land flowing with milk and honey.
The reason why circumcision was omitted in the wilderness, was that the sentence of Numbers 14:28 ff placed the whole nation for the time under a ban; and that the discontinuance of circumcision, and the consequent omission of the Passover, was a consequence and a token of that ban. The rejection was not, indeed, total, for the children of the complainers were to enter into the rest; nor final, for when the children had borne the punishment of the fathers’ sins for the appointed years, and the complainers were dead, then it was to be removed, as now by Joshua. But for the time the covenant was abrogated, though God’s purpose to restore it was from the first made known, and confirmed by the visible marks of His favor which He still vouchsafed to bestow during the wandering. The years of rejection were indeed exhausted before the death of Moses (compare Deuteronomy 2:14): but God would not call upon the people to renew their engagement to Him until He had first given them glorious proof of His will and power to fulfill His engagements to them. So He gave them the first fruits of the promised inheritance - the kingdoms of Sihon and Og; and through a miracle planted their feet on the very soil that still remained to be conquered; and then recalled them to His covenant. It is to be noted, too, that they were just about to go to war against foes mightier than themselves. Their only hope of success lay in the help of God. At such a crisis the need of full communion with God would be felt indeed; and the blessing and strength of it are accordingly granted.