For Christians today the answer is simple:
6Jesus said to him, “I am the way, and the truth, and the life. No one comes to the Father except through me. (John 14:6)
9because, if you confess with your mouth that Jesus is Lord and believe in your heart that God raised him from the dead, you will be saved. (Rom. 10:9)
The BIG question is: Has it always been this way?
How were the Old testament people saved?
The answer to this question is not merely academic. One area that is affected by the answer is how gentile Christians today think of Jewish non-Christians today.
I recently came across a “Messianic” organisation with ex-Christians having rejected the idea of Jesus being both God and Man. They think of Jesus as the Messiah but not as God. For them this is a logical consequence of the way they read and know the Old Testament. There is a longing for a red thread through the Bible. They have understood that the Bible must be coherent – that the God of the Old Testament remains the same in the New Testament.
They argue that if the Old Testament is Jewish, then the New Testament must be Jewish. ‘Jewish’ is defined as rabbinic Judaism defines it. God is a singularity, a monothone. God is one person as he is in Islam. God remains the same.
And yes, they are right – God remains the same. But rather than the faith being ‘Jewish’ all along, it is ‘Christian’ all along. The faith of the Bible – the whole Bible – centres on the gospel of Jesus.
‘Jewish’ was and is a national identity. Many Jews were and are Christian (Abraham, Moses, David, Peter, Paul…), which is the faith of the Bible and the identity of the God of the Bible (trinity). As a rejection of Jesus the national identity of ‘Jewish’ with time became equalled with a separate religion.
Lets look at how the New Testament views the faith of the Old Testament (my emphasis added):
1 Pet. 1:8-12 as it:
8 Though you have not seen him, you love him. Though you do not now see him, you believe in him and rejoice with joy that is inexpressible and filled with glory, 9obtaining the outcome of your faith, the salvation of your souls.
10Concerning this salvation, the prophets who prophesied about the grace that was to be yours searched and inquired carefully, 11inquiring what person or time the Spirit of Christ in them was indicating when he predicted the sufferings of Christ and the subsequent glories. 12 It was revealed to them that they were serving not themselves but you, in the things that have now been announced to you through those who preached the good news to you by the Holy Spirit sent from heaven, things into which angels long to look.
Peter in Acts 10:42-43:
42And he commanded us to preach to the people and to testify that he is the one appointed by God to be judge of the living and the dead. 43 To him all the prophets bear witness that everyone who believes in him receives forgiveness of sins through his name.”
Paul writes to Timothy (2 Tim. 3:14-15):
14But as for you, continue in what you have learned and have firmly believed, knowing from whom you learned it 15and how from childhood you have been acquainted with the sacred writings, which are able to make you wise for salvation through faith in Christ Jesus.
Paul writes in Rom 3:20:
20For by works of the law no human being will be justified in his sight, since through the law comes knowledge of sin. 21But now the righteousness of God has been manifested apart from the law, although the Law and the Prophets bear witness to it— 22the righteousness of God through faith in Jesus Christ for all who believe. For there is no distinction: 23for all have sinned and fall short of the glory of God, 24 and are justified by his grace as a gift, through the redemption that is in Christ Jesus,
Paul gives the example of Abraham’s faith in Rom. 4:10-11:
10How then was it counted to him? Was it before or after he had been circumcised? It was not after, but before he was circumcised. 11 He received the sign of circumcision as a seal of the righteousness that he had by faith while he was still uncircumcised. The purpose was to make him the father of all who believe without being circumcised, so that righteousness would be counted to them as well,
15We ourselves are Jews by birth and not Gentile sinners; 16yet we know that a person is not justified by works of the law but through faith in Jesus Christ, so we also have believed in Christ Jesus, in order to be justified by faith in Christ and not by works of the law, because by works of the law no one will be justified.
16Now the promises were made to Abraham and to his offspring. It does not say, “And to offsprings,” referring to many, but referring to one “And to your offspring,” who is Christ. 17This is what I mean: the law, which came 430 years afterward, does not annul a covenant previously ratified by God, so as to make the promise void.
God is true to his word. He makes a promise and he keeps it. This is the frame within we must try to understand the historical development of the Bible. The giving of the Law cannot have changed the promises given to Abraham.
21Is the law then contrary to the promises of God? Certainly not! For if a law had been given that could give life, then righteousness would indeed be by the law. 22But the Scripture imprisoned everything under sin, so that the promise by faith in Jesus Christ might be given to those who believe.
Paul’s simple yet irrefutable point is that if the law could have imputed righteousness to its doers, then Christ would not have had to die.
I do not nullify the grace of God, for if righteousness were through the law, then Christ died for no purpose.
This key OT verse is quoted by Paul:
4“Behold, his soul is puffed up; it is not upright within him,
but the righteous shall live by his faith.
16For I am not ashamed of the gospel, for it is the power of God for salvation to everyone who believes, to the Jew first and also to the Greek. 17For in it the righteousness of God is revealed from faith for faith, as it is written, “The righteous shall live by faith.”
The way to salvation is and has always been through faith in Christ and Christ alone.
This is glorious since it frees us to under no circumstances need to seek to earn our salvation since it is impossible.
And so what we read first is of course an eternal truth:
Jesus said to him, “I am the way, and the truth, and the life. No one comes to the Father except through me.