The writer of Hebrews was encouraging Jews to keep the faith. Many of them had been indoctrinated into Judaism and there was undoubtedly pressure on them to return. They were warned not to "drift away" (Heb 2:1) and not to "neglect so great a salvation" (:3). The gospel is "the power of God for salvation to every one who believes" (Ro 1:16) because "in it the righteousness of God is revealed from faith to faith" (:17). "It was at the first spoken through the Lord" (Heb 2:3) and "God [was] also bearing witness with them" (:4). Then "it was confirmed to us by those who heard" (:3). The author reminds them to "pay much closer attention to what we have heard" (2:1). He asks "how shall we escape?" (:3) if we ignore what we have heard. He warns about "falling away from the living God" (3:12) "whose house we are" (:6). Not "any one of you should seem to have come short of [the promise]" (4:1). We are "partakers of a heavenly calling" (3:1) and "partakers of Christ" (:14). It is because "we have had good news preached to us" (4:2). But it is necessary to "hold fast our confidence" (3:6) and "the beginning of our assurance" (:14). We are to cling to "the boast of our hope firm until the end" (:6). The author goes as far as to say "let us fear while the promise remains" (4:1). The danger is that "you be hardened by the deceitfulness of sin" (3:13). "Today, if you would hear His voice, do not harden your hearts" (Ps 95:7-8). "Take care, brethren, lest there should be any one of you an evil, unbelieving heart" (Heb 3:12).
God led Israel out of Egypt. Even then Hebrews explains that "the gospel was preached to us as well as to them" (Heb 4:2). Unfortunately God explains, "'It is a people who go astray in their hearts, and they do not know My ways.' So I swore in My wrath, they shall not enter My rest" (Ps 95:10). "There remains a rest for the people of God" (Heb 4:9). "But the word which they [Israel] heard did not profit them, not being mixed with faith in those who heard it" (:2). "He who entered His rest has himself also ceased from his works as God did from His" (:10). God's plan was implemented via Israel. Paul reminds "that you were at that time separate from Christ, excluded from the commonwealth of Israel, and strangers to the covenants of promise, having no hope and without God in the world" (Eph 2:12). "God was in Christ reconciling the world to himself" (2Co 5:19). His purpose was "through Him to reconcile all things to Himself, having made peace through the blood of His cross" (Col 1:20) which "put to death the enmity" (Eph 2:16). "He has now reconciled you in His fleshly body through death, in order to present you before Him holy and blameless and beyond reproach" (Col 1:22). He reconciled "both [Jew and Gentile] in one body to God through the cross" (Eph 2:16). Paul encourages "on behalf of Christ, to be reconciled to God" (2Co 5:20). "Having been reconciled, we shall be saved by His life" (Ro 5:10).
The author of Hebrews links his message to "'the day of trial in the wilderness, where your fathers tried Me by testing Me, and saw My works for forty years'" (Heb 3:8-9). They hardened their hearts (:8) and "were disobedient" (:18). "They are a people who err in their heart and they do not know My ways" (Ps 95:10). They heard the word but it "did not profit them, because it was not united by faith" (Heb 4:2). God had told them to survey Canaan and "send a man from each of their fathers' tribes, every one a leader among them" (Num 13:2). Caleb reported, "'We should by all means go up'" (13:30) for "'if the Lord is pleased with us, then He will bring us into this land, and give it to us'" (14:8). But the majority "gave out to the sons of Israel a bad report" (13:32) and caused the congregation to respond, "'Why is the Lord bringing us into this land to fall by the sword'" (14:3). They then said "to stone them [Joshua and Caleb] with stones" (:10). They were "not able to enter because of unbelief" (Heb 3:19). God then declared, "'They shall by no means see the land which I swore to their fathers, nor shall any of those who spurned Me see it" (Num 14:23). God cited "'all the men who have seen My glory and My signs, which I performed in Egypt and in the wilderness'" (:22). But they did not unite their observations with faith (Heb 4:2), "'have not listened to My voice'" (Num 14:22) and therefore "they do not know My ways" (Ps 95:10). God said they "'yet have put me to the test ten times'" (Num 14:22). Of the twelve spies, ten of them were negative.
Nonetheless, God had a plan. "'Indeed, as I live, all the earth will be filled with the glory of the Lord'" (Num 14:21). "My servant Caleb, because he has had a different spirit and has followed Me fully, I will bring into the land which he entered, and his descendants shall take possession of it" (:24). The unbelieving ones "failed to enter because of disobedience" (Heb 4:6). Therefore "be diligent to enter that rest lest anyone fall through following the same example of disobedience" (:11). "We who have believed enter that rest" (:3). "One who has entered His rest has also rested from his works" (:10). Jesus leads the way where he "has entered as a forerunner for us" (6:20) "who has passed through the heavens" (4:14). He is "one who has been tempted in all things as we are yet without sin" (:15). Therefore "let us hold fast our confession" (:14) and "draw near with confidence to the throne of grace that we may receive mercy and may find grace to help in time of need" (:16).