Galatians 3:8
And the scripture, foreseeing that God would justify the heathen through faith, preached before the gospel unto Abraham, saying, In thee shall all nations be blessed. And the scripture, foreseeing that God would justify the heathen through faith, preached before the gospel unto Abraham, saying, In thee shall all nations be blessed.
God preached the gospel to Abraham beforehand in the promise that blessing would come to all nations through him and through his seed. That promise pointed to Christ, the coming Saviour and Redeemer. The gospel so given was the covenant of grace first made in Eden and renewed to Abraham, the same gospel brought to Adam in the promise of a Redeemer to bruise the serpent's head and preached to Jacob and to Moses, and the same gospel preached today bringing the same hope.
The former dispensation and the period of the Jewish economy were therefore not a Christless time without mercy or grace, but a time of wonderful manifestations of divine power and presence, in which people were saved through Christ just as people are now. God also taught Abraham the gospel through type, especially the offering of Isaac, where the ram offered in place of Isaac represented the Son of God to be sacrificed in the stead of humanity doomed to death by transgression of God's law, the Father giving a ransom so the sinner may live. The command to slay his son both tested Abraham's faith and impressed his mind with the reality of the gospel, permitting the agony of that trial so that from his own experience he might understand something of the greatness of the infinite God's sacrifice for human redemption.
That gospel included the system of sacrifices devised by Christ and given to Adam and through Moses to Israel, typifying a Saviour to come who would bear the sins of the world and die for its redemption and representing Christ's own ministry and death. Abraham understood that the promise pointed to Christ, fixed his faith upon the Redeemer to come, rejoiced to see Christ's day by faith, looked to Jesus as the Author and Finisher of faith, trusted in Christ for forgiveness of sins, and his faith was counted to him for righteousness. The covenant thus renewed offered to all pardon and the assisting grace of God for future obedience through faith in Christ, promised eternal life on condition of fidelity to God's law, gave the patriarchs the hope of salvation, and maintained the authority of God's law.
The promise foretold that people from every nation would be justified through faith. Abraham's seed means all who through Christ become children of faith, not Israel according to the flesh, so although literal Israel failed its high destiny to be the light of the world, failed in unbelief, despised God's mercy, and forfeited its blessings as His chosen people, God had not cast off the seed of Abraham and the glorious purposes undertaken through Israel would still be fulfilled. All believers are counted as Abraham's seed and inheritors of the covenant promises, without outward status or disadvantage determining who may share its spiritual blessings.
That blessing is fulfilled as Jews and Gentiles are united through the fruit of obedience, as God's people live out His law and show His character to the world through goodness, mercy, justice, and love. Like Abraham, believers are called to guard and make known to the world the law of God and the gospel of His Son, and the light of the gospel shining through the disciples of Jesus to those in darkness, with thousands from Gentile lands flocking to its rising brightness, is the increase and prosperity of Israel. The promises to Abraham and his posterity, and through Christ to the nations, may appear unconditional but are conditional, so whether Abraham would share in their fulfillment was determined by the course he pursued.
Abraham worked in harmony with God and faithfully performed his part in the great plan by his faithfulness in governing his household, firmly restraining evil and promoting justice and godliness among them by precept and example, which God approved. Abraham was to represent Christ, and his work with that of other representative men would shine the light of truth and awaken expectation of the One who would accomplish a great work. The Abrahamic covenant is the covenant of grace by faith in Christ Jesus, so hope comes only by coming under that covenant, not by seeking to live by legal religion and fulfill the claims of the law in human strength, which produces the spirit of bondage.