I keep coming across the idea that Old Testament believers didn’t need to know (a) God in three persons or (b) Jesus Christ himself, in order to be saved – as if, prior to Christ’s coming, it was enough for them to know (i) there is one God and (ii) he is Jehovah. But this is a very misguided idea, as you can tell from both the NT and the OT. I might try some other time to talk about the Old Testament evidence that salvation prior to the incarnation was nevertheless only by faith in Christ, but for the time being, here are some points thrown together on the evidence from the New Testament.
1. We know from the New Testament that nobody in the history of the world has ever been saved without a personal faith in Christ the Saviour: so, if the people in the Old Testament didn’t know about Christ, they couldn’t believe in him- ie, they couldn’t have been saved (even the term ‘Old Testament believer’ wouldn’t make sense). But some people in the Old Testament were saved; therefore, they must have had a personal faith in Christ the Saviour, just the same as believers in the New Testament.
2. We have Christ’s own word for it, that the Old Testament Scriptures testify of him. In addition, he gave the instruction to his contemporary Jewish hearers to search their own scriptures in order to find him – which assumes that he can actually be found there, to Old Testament eyes and Old Testament understandings, ie himself as he really is: distinct from the Father, yet God himself, and the Saviour who is revealed to be believed in.
For a specific example, Christ said that in the Old Testament times, before he actually came to the world, Abraham saw his day and was glad for it – and that’s not just the historical time, but the day which belonged to this person Christ.
3. The faith that Abraham had in God is given by Paul as an example for NT believers to follow: we walk in the steps of the faith of our father Abraham, Rom 4:12, and, this faith is the faith of Jesus Christ (Rom 3:22). It’s even more explicit in Galatians 3: those who are of faith (ie, believers) are blessed along with faithful Abraham (v9 & 7): Christ has redeemed us so that the blessing of Abraham would come through Jesus Christ (v13-14). The promise of a seed which was made to Abraham was in fact the promise of Christ (v 16). There are two parts to the argument Paul’s making – (a) that if a person is going to be saved by faith, it has to be the same faith as Abraham had – and (b) equally strongly, that the only faith which saves is faith in Christ the Saviour. In other words, when he encourages NT believers to have and follow in the same faith as the OT believers had, he was only saying the same as he said elsewhere encouraging us to have faith in Jesus Christ.
Similarly, the faith that Abel had is given in Hebrews 11 as one of many examples of people who had the faith that justifies: reading from ch 10 v23 (The just shall live by faith), the argument is that just as we believe to the saving of the soul, so Abel had faith. The faith that all the OT believers had, is given to the NT church as an example of the exact same faith that we should have: the people cited are Abel, Enoch, Noah, Abraham, Isaac, Jacob, Joseph, Moses, Rahab, Gideon, Barak, Samson, Jephthae, David, Samuel, the prophets and a host of other men and women. Their histories are provided so that they can be examples of witnesses for us, us in the New Testament, so that we too would be encouraged to look to Jesus, the author and finisher of the very same faith.
4. When expositions of the OT scriptures are given in the NT, they focus on identifying Jesus Christ as the same Messiah as was believed in under the OT. Paul told Agrippa that he said none other things than those which the prophets and Moses said would come to pass: namely that Christ would suffer, and rise from the dead, and show light to the people and the Gentiles, Acts 26:22-23. Isaiah saw his glory and spoke of him, John 12:37-41. As early as the seventh generation after the creation, Enoch prophesied that the Lord was coming, Jude 14-15. David spoke concerning him, I saw the Lord always before my face … (Acts 2:22-28). In fact, Let me freely speak to you of the patriarch David: David being a prophet seeing this before spoke of the resurrection of Christ, ie this Jesus who God has raised up, Acts 2:29-32.
A couple more quick points to finish up with.
– Of course this doesn’t mean that all the OT believers had the same quantity of knowledge as we do, in the sense that, if they gave a list of all the facts they knew about the promised Saviour and explained how those facts fitted together, that would be a shorter list than we could give and an explanation with more bits missing. But the facts which they did know, were the crucial facts to know about the Saviour: that he would be man as well as God and that he was to die for the sins of his people. The Lord Jesus Christ is exactly the Messiah who was promised in the Old Testament, and just as today, he is the person who everyone had to believe in if they were going to be saved.
– Calling the faith of the OT believers “the very same faith” as that of NT believers does not mean “the same” by virtue of just being a vague understanding that there is one God. It means it was a laying hold of Christ the second Person of the Godhead as he was appointed by the Father to the work of Saviour and as the merits of his saving work were applied by the Holy Spirit. If they had only known the fact that “there is one God”, that wouldn’t have saved them: lots of people honestly believe that God exists and that there’s only one God – that’s not good enough to save them. The only way of salvation, the only way of access to God for sinners is through a Mediator, someone who is himself great enough and holy enough to approach God, and yet, someone who understands and can stand for the creature. The only person who fits these qualifications is the Lord Jesus Christ, who is God and man, in two distinct natures, and one person, for ever – that’s who all the Old Testament believers believed in for salvation, and that’s who people have to believe in now, today, now that he has come as promised.