The Big Story Has Been the Plan All Along ...

17 What I mean is this: The law, introduced 430 years later, does not set aside the covenant previously established by God and thus do away with the promise. 18 For if the inheritance depends on the law, then it no longer depends on the promise; but God in his grace gave it to Abraham through a promise.

...

21 Is the law, therefore, opposed to the promises of God? Absolutely not! For if a law had been given that could impart life, then righteousness would certainly have come by the law. 22 But Scripture has locked up everything under the control of sin, so that what was promised, being given through faith in Jesus Christ, might be given to those who believe.

C.S. Lewis - Man or Rabbit

Mere morality is not the end of life. You were made for something quite different from that. J. S. Mill and Confucius (Socrates was much nearer the reality) simply didn't know what life is about. The people who keep on asking if they can't lead a decent life without Christ, don't know what life is about; if they did they would know that 'a decent life' is mere machinery compared with the thing we men are really made for. Morality is indispensable: but the Divine Life, which gives itself to us and which calls us to be gods, intends for us something in which morality will be swallowed up. We are to be re-made. All the rabbit in us is to disappear - the worried, conscientious, ethical rabbit as well as the cowardly and sensual rabbit. We shall bleed and squeal as the handfuls of fur come out; and then, surprisingly, we shall find underneath it all a thing we have never yet imagined: a real Man, an ageless god, a son of God, strong, radiant, wise, beautiful, and drenched in joy. '

'When that which is perfect is come, then that which is in part shall be done away.'2 The idea of reaching 'a good life' without Christ is based on a double error. Firstly, we cannot do it; and secondly, in setting up 'a good life' as our final goal, we have missed the very point of our existence. Morality is a mountain which we cannot climb by our own efforts; and if we could we should only perish in the ice and unbreathable air of the summit, lacking those wings with which the rest of the journey has to be accomplished. For it is from there that the real ascent begins. The ropes and axes are 'done away' and the rest is a matter of flying.

23 Before the coming of this faith,[j] we were held in custody under the law, locked up until the faith that was to come would be revealed. 24 So the law was our guardian until Christ came that we might be justified by faith. 25 Now that this faith has come, we are no longer under a guardian.

26 So in Christ Jesus you are all children of God through faith, 27 for all of you who were baptized into Christ have clothed yourselves with Christ. 28 There is neither Jew nor Gentile, neither slave nor free, nor is there male and female, for you are all one in Christ Jesus. 29 If you belong to Christ, then you are Abraham’s seed, and heirs according to the promise.