Kaiser explains the relationship between faith and faithfulness or obedience in the receipt of the promises by Abraham and his seed:
The third and climactic element in the promise [of the Abrahamic covenant] was that Abraham and each of the successive sons of promise were to be the source of genuine blessing; indeed, they were to be the touchstone of blessing to all other peoples on the earth. All nations of the world would be blessed by them, for each was the mediator of life to the nations (of Abraham—12:3; 18:18; 22:17–18; of Isaac—26:3–4; and of Jacob—28:13–14).
The apostle Paul would later point to this phrase (“all the peoples on earth will be blessed through you,” Ge 12:3), and declare that it was the same “gospel” he preached (Gal 3:8). Simply put, the good news was that “in [the promised seed] all the nations of the earth shall be blessed” (Gal 3:8). Thus the embryo of God’s good news could be reduced to the linchpin word “blessing.” The one who was blessed was now to be the conduit of blessing of universal proportions to the whole world. In contrast to the nations who sought a “name” merely for themselves, God made Abraham a great name so that he might be the means of blessing all the nations on earth.
But, it might be asked, how were the nations to receive this blessing mediated by Abraham or any of his successive sons? The method must be the same as it was for Abraham. It would be by faith: “Abram believed the Lord, and he credited it to him as righteousness” (Ge 15:6).
The literal rendering of Genesis 15:6 is simply he believed in [Jehovah] (he’emîn ba YHWH). This, of course, was more than a vague intellectual assent to a supreme deity in which he decided merely to become a theist. The object of his faith was to be found in the content of the total promise. As such, priority may be given to the oldest, most ancient, and most central part of that promise: the person or the man of promise signified by that male descendant who was to come from the seed (3:15). Indeed, when God first met Abraham, the issue of progeny was not specifically included but only inferred (12:1–3), for the first clause promised to make Abraham into a great nation. His trust, then, was in the Lord—but particularly in the Lord who had promised. . . .
Since the verb “to believe” in Genesis 15:6 is the Hebrew hiphil form (the causative stem) of the verb ’āman (cf. English “amen”), Geerhardus Vos pointed to the “causative-productive sense” of the verb and to the preposition. Both, in his judgment, showed that faith had its source and its object in the personal [Jehovah]. For Abraham, it meant he had to renounce all his human efforts to secure the promise (as witnessed by his attempting at first to legally adopt Eliezer as his son and the inheritor of his estate, Ge 15:2), and he had to depend on the same divine person who had spoken of the future to work in the present as well as the future, to accomplish what he said he would do. Thus, Abraham possessed the promises of God, as yet unrealized, when he possessed the God of the promises and his trustworthy word, even though he never got to enjoy the reality of the content of the promise—the land itself—during his lifetime. . . .
In Genesis 22:16–18 Abraham was told, “Because (kî ya’an ‘ašer) you have done this and have not withheld your son, your only son, I will surely bless you . . . because (‘ēqeb ’ašer) you have obeyed me.” In Genesis 26:5 the blessing is repeated to Isaac “because (‘ēqeb ’ašer) Abraham obeyed me and did everything I required of him, keeping my commands, my decrees and my instructions.” In my judgment, the conditionality was not attached to the promise, but only to the participants who would benefit from these abiding promises. If the condition of faith was not evident, then the patriarch would become a mere transmitter of the blessing without personally inheriting any of its gifts directly. Such faith must be evident also in an obedience that sprang from faith. Certainly, the promise was not initiated in either chapter 22 or 26; that had long since been settled. But each chapter did have a sensitive moment of testing or transition. Furthermore, the election of God had been with a purpose not only of blessing Abraham and the nation (18:18) but also of charging him and his household to “keep the way of the Lord by doing what is right and just, so that (lema‘an) the Lord will bring about for Abraham what he has promised him” (v. 19).
The connection is undeniable. The duty of obedience (law, if you wish) was intimately tied up with promise as a desired sequel. Therefore, the transition to the coming time of Mosaic law should not be all that difficult for any who had really adequately listened to the full revelation of the promise in the patriarchal era. But in no way was the promise-plan itself dependent on anyone’s obedience; it only insured their participation in the benefits of the promise but not on its maintenance. (pgs. 59-61, The Promise-Plan of God: A Biblical Theology of the Old and New Testaments, Walter Kaiser. Grand Rapids, MI: Zondervan, 2008)
One should note that the Lord does not merely promise Abraham’s descendants the land of Canaan, but indicates that the patriarch himself will inherit the land (Genesis 13:15, 17; 15:7)—something that will take place after the resurrection in the Millenial kingdom when Abraham will dwell in Canaan with true Israel. Such a resurrection, and the eternal felicity associated with it, is also involved in the fact that Jehovah is truly a God to Abraham (Genesis 17:7; 28:13; Exodus 3:6; Matthew 22:32; Mark 12:26). Abraham’s faith led him to look both for the promised kingdom and “for a city which hath foundations, whose builder and maker is God” (Hebrews 11:8-10), the New Jerusalem.
Because of Abraham’s faith in the Christ set forth in the Abrahamic covenant, as expressed in Genesis 15:6, God formally ratified that covenant with the patriarch (Genesis 15:7-22) and promised him that his seed would inherit the land. Life in the Promised Land (Genesis 15:18-22) is specified as given, by grace and for Christ’s sake, to both Abraham personally and to his seed for ever, and ultimately to Christ as head over them all, as Abraham and his corporate and Messianic seed will possess the Land in the resurrection during the Millenial kingdom and eternal state.[i] As eternal salvation is an undeserved gift of grace, so neither Abraham nor any of his fallen physical descendents possessed the Land in their lifetime, or will possess the Land in the eschaton, because of their inherent worthiness; the inheritance is solely procured by grace (Deuteronomy 9:4-6; cf. Romans 10:8 & Deuteronomy 30). Kaiser properly notes, concerning the unity and plurality of the “seed” concept:
When [Jehovah] appeared to Abraham, after the patriarch had arrived at Shechem, that ancient word about a “seed” (3:15) was again revived. Now, however, it was directed to Abraham (Ge 12:7). From there on, the importance of this gift of a child who would inherit the promises and blessings became one of the dominant themes in the patriarchal narrative, appearing, all told, some twenty-eight times. [Genesis 12:7; 13:15, 16 (2C); 15:13, 18; 16:10; 17:7, 8, 9, 10, 13, 16, 19; 21:12; 22:17 (2×), 18; 24:7; 26:3, 4 (3×), 24; 28:13, 14 (2×); 32:12; 35:12; 48:3, 4.] Eve had been promised both a “seed” and a male individual—apparently from that “seed.” Now in the progress of revelation, with much greater specification added, the concept was elaborated both on the corporate (all who believed) and representative (Man of promise/“Seed”) aspects of this promised heir. It was to encompass so great a number that, in hyperbolic fashion, they would rival the stars of heaven and the sands on the seashore. But this “seed” would also be another “son”—born at first to Abraham, when all hope of his ever having children was lost, and then continued in the one born to his son Isaac, and later to the one born to Isaac’s son Jacob. A line of successive representative sons of the patriarchs who were regarded as one with the whole group they represented matched the seminal idea already advocated in Genesis 3:15. Furthermore, in the concept of “seed” were the two aspects: (1) the seed as a future benefit and (2) the seed as the present beneficiaries of God’s temporal and spiritual gifts. Consequently, “seed” was always a collective singular noun; few times did it have the meaning of a plural noun (as in “descendants”). Thereby the “seed” was marked as a unit, yet with a flexibility of reference: now referring to the one person, now to the many descendants of that family. This interchange of reference with its implied “corporate solidarity” was more than a cultural phenomena or an accident of careless editing; it was an integral part of its doctrinal intention. . . . Thus, we refer to the “one” and the “many” when we refer to the “seed,” or “offspring,” but the use of the translation “descendants” limited the reference only to the whole group who believed but did not include the representative of the whole group, the coming Messiah himself. (pgs. 56-57, The Promise-Plan of God: A Biblical Theology of the Old and New Testaments, Walter Kaiser. Grand Rapids, MI: Zondervan, 2008)
This recognition of both the individual and corporate aspect of the “seed” continues in the New Testament (cf. Galatians 3:16, 29).
The promise of life was given to Abraham because he believed in Jehovah, not because of any works that he did, setting a pattern for all those who are of Abraham—for Abraham is the father of believing Jews and Gentiles—to also receive life in the kingdom, spiritual life now and eschatological life, through faith, through which they are accouted righteous (Romans 4). Thus, believers are those who receive salvation,[ii] those who are established and prosper, both in having Jehovah bless them and protect them in the Land and in general by having all things work together for good to them (2 Chronicles 20:20). They believe in Jehovah alone and reject any confidence in other gods (Isaiah 43:10). They will be secure and protected by the virgin-born yet Divine Messiah from the temporal and eternal judgments that fall on the wicked.[iii] They are the faithful who are saints or holy ones (Hosea 11:12), having been converted and having in this manner become the righteous (Hosea 14:1-9). On the other hand, those who do not believe are those who are the objects of God’s wrath and judgment, those who do not inherit the Promised Land[iv] but are killed by plagues or the sword, or suffer exile from it as they turn to idolatry and are the objects of the Lord’s great anger.[v] They are those who are removed from the Land in their lifetime (cf. Psalm 78) and will not inherit it in the Millenium or the eternal state, but are eternally cut off from true Israel,[vi] having not set their hope[vii] in God, but rejected His covenant, and been rebellious and faithless.[viii] They are those who are not established in time or in eternity in the Land because they do not believe in Jehovah and Immanuel, the Posessor and Protector of the promised country,[ix] the Stone and sure foundation of Israel,[x] the Servant who would justify many by the offering of Himself.[xi] There are no texts where true believers are lost or cast off because of a lack of circumcision, obedience to various commandments, or anything else; in continuity with the New Testament, the Old Testament teaches that all believers receive salvation and all unbelievers receive condemnation.[xii] Thus, following the pattern set in Genesis 15:6, believers are those who receive salvation in its temporal and eternal aspects, and unbelievers are those who receive temporal and eternal judgment.
[i] Genesis 13:15; 17:8; 28:13.
[ii] Exodus 14:31-15:2. While the entire nation of Israel received salvation in that they were delivered from slavery in Egypt and from Pharaoh’s army, although the entire nation did not believe in an eternally saving fashion, nonetheless Exodus 14:31-15:2 does connect belief and salvation, and both the belief and the salvation received and sung about pass beyond the merely physical and temporal for the Israel of God (Romans 9:6) to encompass all that is involved, both temporally and eternally, in the affirmation “Jehovah . . . is become my salvation: he is my God.”
[iii] Isaiah 28:16; 8:14-15; 7:14; 9:6; Romans 9:33; 10:11.
[iv] Numbers 14:11-35; 20:12; Deuteronomy 1:32-40; 9:23-24. Numbers 14:11-35 speaks, at least in general, of those who do not believe in Jehovah at all, while Numbers 20:12 speaks of a lack of faith in the Lord in a particular situation by those who are true sons of Israel, namely, Moses and Aaron. The language employed concerning those who do not believe in the Lord at all in Numbers 14:11-35 is much harsher than that in Numbers 20:12, although entrance into the Promised Land is taken from both groups. It is noteworthy that Deuteronomy 1:32-40 indicates that the Lord was angry with Moses because of the larger unbelieving multitude that he led and represented (as, typologically, there is no problem with the Law itself, but because of sin, man is unable to receive eternal life through the Law), those who were rebellious all the time that Moses knew them and consequently did not believe nor hearken to the Lord (Deuteronomy 9:23-24).
[v] 2 Kings 17:7-23; Deuteronomy 27-28. Contrast the unbelief of 2 Kings 17:14 with Hezekiah’s “trust” in 18:5 and the temporal prosperity that was consequent upon it.
[vi] Exodus 30:33, 38; 31:14; Leviticus 7:20, 21, 25, 27; 17:4, 9; 18:29; 19:8; 20:17, 18; 23:39; Numbers 9:13; 15:30; Deuteronomy 10:16, 30:6; Psalm 125:5; Isaiah 53:8; Jeremiah 4:4; Daniel 9:26; Zechariah 14:2.
[vii] lRsR;k, Psalm 78:7; cf. Job 8:14; 31:24; Proverbs 3:26.
[viii] Psalm 78; cf. v. 7, 22, 32, 37.
[ix] Isaiah 53:1; 7:9-14; 8:8; 9:6; Hebrews 11:14.
[x] Isaiah 28:16; 8:14; Genesis 49:24; Psalm 118:22; Romans 9:33; 10:11; 1 Peter 2:4-8).
[xi] Isaiah 52:13-53:12.
[xii] An affirmation that all true believers receive salvation in the Old Testament, as in the New, does not eliminate the possibility that one could, in Old Testament times, possess a type of spurious “faith” that fell short of the kind of true faith associated with real conversion, just as such spurious “faith” is mentioned in the New Testament (John 2:23-25) while salvation is still set forth as by means of faith alone (John 3:1-21). The Old Testament indicates that one could assent, for example, to the fact that the Word from the Lord was true without having anything more than the “faith” of a hypocrite (Psalm 106:12ff.), while at the same time repeatedly stressing the salvation of all believers (Genesis 15:6).