Other than Joshua and Caleb, did the first generation of Egypt lose their salvation because they were not permitted to proceed into the Promised Land?
In brief, no! Although the Israelites of the age of 20 and above, excepting Joshua the son of Nun and Caleb the son of Jephunneh, were not allowed to realize the purpose of their deliverance (their salvation) from Egypt, which was to be the establishment of a theocratic kingdom in the Promised Land, their deliverance (salvation) from Egypt was permanent and secure. Their salvation was the result of God’s recognition of their faith by their sacrifice of the paschal lamp, i.e., the blood on the doorposts and lintel of each Israeli home during their last night in Egypt. It was due to their belief God’s Word pertaining to this prescribed sacrifice that brought about their salvation from Egypt. And in this Old Testament type is seen the New Testament antitype, the eternal (spirit) salvation of Christians who place their faith in the vicarious (substitutionary) sacrifice of the Paschal Lamb, Jesus Christ, while on the cross of Calvary — a salvation that is irrevocable regardless of whether or not they realize the purpose of their deliverance, the salvation of their souls, which salvation pertains only to the heavenly portion of the Theocratic Kingdom that will be established at Christ’s Second Advent to earth during the Messianic Era.
Note commentary on this type-antitype arrangement by Chitwood :
Blood and Leaven
For I will pass through the land of Egypt on that night, and will strike all the firstborn in the land of Egypt, both man and beast; and against all the gods of Egypt I will execute judgment: I am the LORD.
Now the blood shall be a sign for you on the houses where you are. And when I see the blood, I will pass over you; and the plague shall not be on you to destroy you when I strike the land of Egypt.
So this day shall be to you a memorial; and you shall keep it as a feast to the LORD throughout your generations. You shall keep it as a feast by an everlasting ordinance.
Seven days you shall eat unleavened bread. On the first day you shall remove leaven from your houses. For whoever eats leavened bread from the first day until the seventh day, that person shall be cut off from Israel. (Exodus l2:l2-l5)
There is a dual truth taught in Exodus chapters twelve and thirteen concerning the application of blood and the expelling of leaven. These chapters introduce the first two “feasts of the Lord” in the prophetic calendar of Israel — the “Passover” and the “Feast of Unleavened Bread” (cf. Leviticus 23:1ff). “Blood” from the paschal lambs was to be applied first. Then, those who had applied the blood were to put “leaven out of their houses.” This is the unchangeable order established by God in the book of Exodus.
In these two chapters, the sentence of death had fallen upon the firstborn throughout all the land of Egypt (Exodus 12:4, 5). The firstborn in every household, Israelite and Egyptian alike, must die. However, provision was made for all the firstborn in Israel to experience death vicariously. Every household was to take a lamb from the flock, the lamb was to be slain, and blood from the lamb was to be applied “on the two side posts and on the upper door post” of every house throughout the camp of Israel.
When the Lord passed through the land of Egypt to execute the sentence of death, He looked for one thing at each house. He looked for the blood upon the entrance way. The presence of blood showed that the firstborn in that household had already died. Death had occurred vicariously through a slain lamb from the flock. The Lord then passed over that house. The absence of blood, on the other hand, showed that the firstborn had not yet died. Death then occurred at the hands of the Lord, for the firstborn in every household MUST die.
It cannot be overemphasized that the only thing which the Lord looked for on this particular night was the blood. “. . . when I see the blood, I will pass over you” (Exodus 12:12, 13). Nothing else was in view; and once the death of the firstborn had been executed, that was the end of the matter. Those who died vicariously held the same position relative to death in the eyes of the Lord as those who died apart from a substitute. The death of the firstborn had occurred in both instances, and God was satisfied. Nothing could, at a later time, be reversed.
In the antitype of this aspect of Exodus chapters eleven and twelve, “Christ our passover is sacrificed for us [‘was sacrificed on our behalf'’]” (1 Corinthians 5:7). His blood was shed; and those who have appropriated His blood, through faith, have died vicariously. Death has occurred through the slain Lamb, as in Exodus chapter twelve. “Christ died for our sins according to the scriptures” (Exodus 12:1-13, 29, 30; John 1:29; 19:16-30; 1 Corinthians 15:3). And an individual availing himself of this provision has already kept the appointment with death referred to in Hebrews 9:27. The death of the firstborn is past, God is satisfied, and that is the end of the matter. As in Exodus chapter twelve, nothing can, at a later time, be reversed.
Following the Passover in Egypt, God dealt with the Israelites on an entirely different plane. The Israelites, from this time forward, were dealt with on the basis of that which had occurred in Egypt, NEVER relative to this matter. And it is the same with Christians today. Christians are dealt with strictly on the basis of that which Christ has done on their behalf, NEVER relative to this matter.
Immediately following the Passover, the Feast of Unleavened Bread commenced. Beginning with this festival, God dealt with the Israelites relative to “leaven” in their houses, NOT relative to that which had previously occurred (the death of the firstborn) and was now a past, finished matter. They were to put leaven out of their houses, and they were to eat unleavened bread for seven days. “Seven” is God’s number, as “six” is man’s number. “Six” shows incompleteness, and “seven” shows completeness, with “eight” indicating a new beginning. The Israelites were to put leaven out of their houses and eat unleavened bread for seven days — one complete period of time.
"Leaven points to that which is vile or corrupt; it points to sin in the lives of individuals. And the spiritual significance of this festival surrounded the fact that the Israelites, as God’s redeemed people, were to put that which was vile, corrupt, associated with sin out of the camp for one complete period of time. This period of time had to do with the existence of the nation from that point forward.
An individual Israelite refusing to expel the leaven was cut off from Israel” (cf. Exodus 12:15; Psalm 37:9, 22, 28, 29, 34). He died on the right side of the blood. He was cut off from Israel, not from God. The same held true for the entire accountable generation subsequently cut off following events at Kadesh-Barnea. They too died on the right side of the blood. Their failure to enter into the land, resulting in their overthrow in the wilderness, had no bearing upon their standing before God on the basis of that which had previously occurred the night of the Passover in Egypt.
The entire matter is the same in Christendom today. Christians are commanded to “keep the feast,” which is to be done in a new way, “with the unleavened bread of sincerity and truth” (1 Corinthians 5:8). Christians are to put that which is vile, corrupt, associated with sin out of their lives for one complete period of time — the entire duration of the Christian life.
Christians refusing to expel the leaven will, as the Israelites who refused to expel the leaven, be “cut off.”
The Israelites under Moses were called out of Egypt to go into another land and realize an inheritance awaiting the nation. Those cut off in Israel forfeited the realization of their calling. They fell on the right side of the blood but outside the land to which they had been called.
And so it is with Christians. Those refusing to expel the leaven will forfeit the realization of their calling. They will fall on the right side of the blood but outside the land to which they have been called. Such a failure, as in the type, will have no bearing upon that which previously occurred in their lives through the work of the Son and the Holy Spirit in effecting their standing before God.
Many Christians, because of the sins of the flesh, have their lives cut short during the present time. However, this is not the primary meaning of being “cut off.” Those “cut off” in Israel were separated from a realization of their calling. They were called out of Egypt for a purpose; and most were overthrown, failing to realize the goal of their calling.
Such an overthrow for Christians in the antitype awaits the issues of the judgment seat of Christ, for it is there that decisions and determinations that directly affect Christians relative to their calling will be made. God will not countenance sin in the lives of His people; and before the judgment seat, the harbored sins of Christians will be brought out into the open and dealt with. Those refusing to judge their sins prior to that time, availing themselves of the high priestly ministry of Christ, will then be judged. Their sins then, though, will be dealt with in an entirely different manner; for, at that time, Christ will be their Judge rather than their High Priest (cf. 1 Corinthians 11:31; 1 John 1:9-2:2).
 Judgment Seat of Christ by Arlen L. Chitwood, The Lamp Broadcast, Inc., 2001, pages 5-8