The question surprised me at first, probably because it was asked in a seminary classroom, “how were people in the Old Testament saved?”
Salvation is only through Jesus Christ and always has been, that’s the short answer. But why?
The key is the nature and character of God. He is sovereign over all things so nothing can thwart His will or surprise Him. God is in full control of all things (Ephesians 1:11). His sovereignty ensures that nothing can interrupt or postpone God’s decision for something or anything to happen.
According to Ephesians 1:3-5, God the Father chose “before the foundation of the world” everyone He would save. Based on His sovereignty, how could anything else happen except those whom He specified for salvation will actually be saved? There is no other alternative. If God “works all things according to the counsel of His will” then how could His people not “be holy and blameless before Him”?
But God has not cloaked this entire work in secret. In the passages above He reveals it. Then He has also issued promises through which salvation comes (Romans 10:17). These promises have been declared throughout time, for example: Genesis 3:15, “I will put enmity between you and the woman, and between your offspring and her offspring; he shall bruise your head, and you shall bruise his heel.”; Isaiah 44:22, “Turn to me and be saved, all the ends of the earth! For I am God, and there is no other”; and, John 6:40, “For this is the will of my Father, that everyone who looks on the Son and believes in him should have eternal life, and I will raise him up on the last day”. When God determines before the foundation of the earth who will be saved and doubly ensures it by issuing faithful promises, we have no cause to doubt Him (Hebrews 6:13-20).
So, those in the Old Testament times were saved by trusting in the promises God made. When they believed His promise, they were saved, just as we are in these last days. Romans 8:29-30 gives us the culmination of our thinking – God has already chosen the saved and promised He would provide salvation. Old Testament believers trusted God to provide their salvation. We trust that God has provided our salvation through Jesus Christ. Verse 30 reads, “those whom [God] justified [God] also glorified”. God assures us here that His promise is a promise of reality. It is as solid as if justification (the moment He saved us) and glorification (when we enter heaven as perfect) happened at the same time. There is no difference between God’s promise and reality.