J.I. Packer writes:

If we ask what in a nutshell was God revealing in the biblical period, several things must be said together.

First, God was revealing Himself. He was showing His ‘eternal power and deity’ (Rom. 1:20) as maker and master, and with that His character and His ways with men (see Exod. 34:6f.; 5:9f.; Jer. 9:24; 1 John 1:5; 4:7-10), so that He might be acknowledged and worshipped for all that He is and does and gives. Viewed from this standpoint, revelation reached its climactic point in the incarnate life of God’s Son.

Second, God was revealing His kingdom. He was showing the reality of His universal kingship (note how prophet after prophet saw visions of God’s throne, 1 Kings 22:19; Isa. 6:1ff.; Ezek. 1:26; Dan. 7:9; Rev. 4:2, and how psalmist after psalmist celebrated God’s reign, Pss. 93:1f.; 96:10; 97:1; cf. 1 Chron. 16:31; Isa. 52:7; Rev. 19:6). He was showing too how He moves history on to the final form that His kingship takes, namely the saving reign of Jesus the Messiah, who is already the world’s true Lord (cf. Matt. 28:18; Heb. 1:3, 8f., 13) and who will come one day in glory to bring all persons and powers that deny His rule to an ignominious end (1 Cor. 15:24ff.; Phil. 2:9-11).

Third, God was revealing His covenant. This was and is an imposed relationship: God pledges Himself to men, to bless them, and they pledge themselves to Him, to serve Him. ‘I will be your God, and you shall be my people’ is the relational commitment which God repeats for each new stage of covenant blessing (Gen. 17:7-14; Exod. 19:4-6; Lev. 26:12; Deut. 7:6; 14:2; Jer. 11:3f.; 30:22; 31:33; Ezek. 11:20; 36:28; Zech. 8:8; 2 Cor. 6:16; Rev. 21:3; etc.); it is the covenant slogan throughout the Bible. The new covenant that was made known through Jesus its mediator was better than its predecessor in many ways (see Heb. 8 10), but God’s undertaking to bless both here and hereafter, which is the covenant relationship itself, was the same throughout. The essence of the covenant in all forms of its administration is that God says ‘my people’ and those addressed say in response to Him, and of Him, ‘our God’, ‘my God’. Luther was entirely right to describe Christianity as a matter of personal pronouns. God’s covenant people – faithful Israelites under the Old Testament, disciples of Christ worldwide under the New – are those of whom it can be said, ‘you have come to know God, or rather to be known by God’ (Gal. 4:9). To them are fulfilled God’s ‘precious and very great promises’ (2 Pet. 1:4). Such is the revealed covenant relationship.

Fourth, God was revealing His law, which is His will for all men but which comes as torah (authoritative paternal instruction) to his own people. ‘He declared his word to Jacob, his statutes and ordinances to Israel. He has not dealt thus with any other nation’ (Ps. 147:19f.). In Old Testament times God identified Himself as Father of His people corporately (Exod. 4:22f.; Mal. 1:6); under the New Testament all who receive God’s ‘one and only’ Son (so the NIV perceptively paraphrases ‘only-begotten’, a term implying affection) become Jesus’ brothers by adoption and new birth (John 1:12f.; 20:17; Gal. 4:4-7); and God’s torah, in its dual form of commands and wisdom, was spelt out under both Testaments (by Moses and the prophets under the Old, and by Christ and His apostles under the New) so that God’s children might learn to honour their Father by maintaining the family standards and thus displaying the family likeness.

Fifth, God was revealing His salvation: that is, His work of rescuing folk from whatever threatens to destroy them – Egyptian captivity (Exod. 14:13; 15:2), Babylonian captivity (Isa. 51:5-6, 8), national foes and personal troubles (the Psalms, dozens of times). From this standpoint, revelation reached its climax when God gave the word of the gospel (cf. Gal. 1:11f.), which sets forth the finished work of Christ’s Spirit (cf. Rom. 1:16; Eph. 1:13).

18 Words (formerly God’s Words), chapter 1.