When Jude wrote “ye should earnestly contend for the faith [faithfulness] which was once delivered unto the saints” (v. 3), he was referring to God’s people in the Exodus, “the Lord, having saved the people out of the land of Egypt, afterward destroyed them that believed [trusted] not” (v. 5). God commanded faithfulness to Him, “Thou shalt have no other gods before me” (Exo 20:3), and obedience to Him, “And shewing mercy unto thousands of them that love me, and keep my commandments” (Exo 20:6). Yet His people didn’t trust Him and were destroyed.
While still in Egypt, God declared to His people the land inheritance promised to their fathers Abraham, Isaac, and Jacob, “And it shall come to pass, when ye be come to the land which the LORD will give you, according as he hath promised” (Exo 12:25), “which he sware unto thy fathers to give thee, a land flowing with milk and honey” (Exo 13:5). But God began testing their faithfulness and trust as soon as they crossed the Red Sea, “So Moses brought Israel from the Red sea, and they went out into the wilderness of Shur; and they went three days in the wilderness, and found no water … And the people murmured against Moses, saying, What shall we drink?” (Exo 15:22,24). “And the whole congregation of the children of Israel murmured against Moses and Aaron … ye have brought us forth into this wilderness, to kill this whole assembly with hunger” (Exo 16:2-3). They weren’t trusting Him for their daily provision as His Son would later teach, “Take no thought for your life, what ye shall eat, or what ye shall drink; nor yet for your body, what ye shall put on … Therefore take no thought, saying, What shall we eat? or, What shall we drink? or, Wherewithal shall we be clothed?” (Mat 6:25,31).
The writer of Hebrews defined the gospel as the message God preached to His people in the Exodus, “For unto us was the gospel preached, as well as unto them: but the word preached did not profit them, not being mixed with faith [faithfulness] in them that heard it” (Heb 4:2). That they were “not being mixed” is that “they were not united with those” (HCSB, LEB, TLV), “they did not join in with those” (NET). Ten of the twelve spies “brought up an evil report of the land” (Num 13:32), but Joshua and Caleb exhorted the people, “If the LORD delight in us, then he will bring us into this land, and give it us; a land which floweth with milk and honey. Only rebel not ye against the LORD, neither fear ye the people of the land; for they are bread for us: their defence is departed from them, and the LORD is with us: fear them not” (Num 14:8-9). The people didn’t join themselves with Joshua and Caleb’s faithfulness and trust, “And to whom sware he that they should not enter into his rest, but to them that believed [trusted] not?” (Heb 3:18).
The people failed to trust God at that crucial moment because they had already been sinning and hardening their hearts against Him, “lest any of you be hardened through the deceitfulness of sin” (Heb 3:13). And Paul listed their sins, “Now these things were our examples, to the intent we should not lust after evil things, as they also lusted. Neither be ye idolaters, as were some of them … Neither let us commit fornication as some of them committed … Neither let us tempt Christ, as some of them also tempted … Neither murmur ye, as some of them also murmured … Now all these things happened unto them for ensamples: and they are written for our admonition” (1Co 10:6-11). Those events were written as our examples because that is the gospel message by which we’re saved.
When we sin against God by lusting, idol worshipping, fornicating, testing, and complaining, our hearts harden and we’ll find it difficult to trust God even for the basic necessities of food, water, and clothing. But when we’re keeping His commandments, He breathes into our hearts the confidence to trust Him. It wasn’t that Caleb just had positive thinking but that he had another spirit or breath, “But my servant Caleb, because he had another spirit [breath] with him, and hath followed me fully” (Num 14:24). The majority, however, were in bondage to evil spirits because of their sins.
When God told Joshua, “that thou mayest observe to do according to all the law, which Moses my servant commanded thee … This book of the law shall not depart out of thy mouth; but thou shalt meditate therein day and night, that thou mayest observe to do according to all that is written therein” (Jos 1:7,8), it wasn’t about memorizing Scripture but exhorting each other daily to keep His commandments, “But exhort one another daily, while it is called To day; lest any of you be hardened through the deceitfulness of sin” (Heb 3:13), “the deceitful lusts” (Eph 4:22).
The gospel isn’t a system of theology given to the early church by the apostles that is simply to be believed, “the faith which was once delivered unto the saints.” It’s the message of faithfulness and obedience to God in keeping His commandments, and trusting Him to enter the inheritance we have through Christ.