God's Promises Are Given To Us Through His Son
Augustine was born in north Africa to a pagan Roman father and a Christian Berber mother. He spent his youth as a true pagan and in his Confessions, describes his time in a heretical sect in Rome and how he came to Christ by the grace of God and the preaching of Bishop Ambrose of Milan, who baptized him in 386. Having entered fully into the way of Christ, Augustine returned to Africa and, as Bishop of Hippo, won renown as one of early Church's greatest theologians.
God fixed a time for his promises, and a time for fulfilling what he had promised. The period of his promises was from the time of the prophets up to John the Baptist; and the period for fulfilling what he had promised is from John and henceforward to the end.
God, who is faithful, put himself in our debt, not by receiving anything but by promising so much. A promise was not sufficient for him: he chose to commit himself in writing as well, making, as it were, a contract of his promises, so that when he began to fulfil his promises, we might contemplate in Scripture the order of their accomplishment. The period of prophecy, therefore, was the announcement of the promises.
He promised everlasting salvation and an unending life of blessedness with the angels, and unfading inheritance, everlasting glory, the vision of his own dear face, his sanctuary in heaven, and by the resurrection of the dead, no further fear of death. This is as it were, his final promise, the goal of all our striving, and after we have received it, we shall seek nothing more. But as to the way in which we are to arrive at our final goal, he has revealed this also, by promise and prophecy.
But because God's promises seemed impossible to men - equality with the angels in exchange for mortality, corruption, poverty, weakness, dust and ashes - God not only made a written contract with men, to win their belief but also established a Mediator of his good faith, not a prince or angel or archangel, but his only Son. He wanted, through his Son, to show us and give us the way he would lead us to the goal he has promised.
It was not enough for God to give us his Son merely to point out the way. He made the Son himself the way, so that you might journey with him as your guide, and by him as the way. The Son of God was to come to men, to take human nature to himself, and in this nature to be born as a man. He was to die, to rise again, to ascend into heaven, to sit at the right hand of the Father, and to fulfill his promises among the nations, and after that to come again, to exact now what he had asked for before, to separate those deserving his anger from those deserving his mercy, to execute his threats against the wicked, and to reward the just as he had promised.
All this had therefore to be prophesied, foretold, and impressed on us as an event in the future, in order that we might wait for it in faith, not find it a sudden and dreadful reality.
Augustine of Hippo (354-430)
Hebrews 1:1-5, 2:1-4