The first mention of salvation in Scripture is Genesis 49:18, "I wait for thy salvation, O Jehovah."
The next place we read about salvation is Exodus 14:13, "stand still and see the salvation of Jehovah." It's worthwhile taking a few moments to think about what Exodus can teach us about salvation.
We remember that the children of Israel had been slaves in Egypt for 430 years (Exodus 12:41). God had sent Moses to deliver them from Egypt, but Pharaoh refused to obey God, God having hardened his heart (Exodus 4:21–23). And so God did what He had told Moses He would do when He spoke to Moses in Midian – He killed Pharaoh's son (Exodus 4:23).
The children of Israel – having been warned that God would pass through Egypt, killing all the firstborn sons (Exodus 12:23) – were to put the blood of a lamb on the doorposts and lintels of their doors, and not go out of their houses until morning (Exodus 12:22). God would "pass over" them if they were sheltered behind the blood of the lamb (Exodus 12:23).
God did what He said He would do – what He had told Moses He would do when He spoke to Moses in Midian, before Moses ever stood before Pharaoh (Exodus 4:21–23). God passed through Egypt, killing every firstborn son (Exodus 12:29–30). So the Egyptians sent the Israelites out of Egypt (Exodus 12:31–33).
1 Corinthians 5:7–8 tells us that Christ is our Passover, having died for us. It is His blood that shelters us from judgment. It is in His death that He ensured the wrath of God cannot touch us (John 3:36).
But of course the people of Israel had a long way to go. In fact, the journey was longer than it really had to be, because of the fear that they people would want to return to Egypt, if they took the most direct route (Exodus 13:17–18).
Exodus 14 opens with God instructing the people of Israel to encamp by the Red Sea. And the scripture tells us why: because God intended to destroy Pharaoh by hardening his heart (again!) and luring him into a trap at the Red Sea (Exodus 14:1–4). Now, let's pause to think about that for a moment... we might expect God to ignore Pharaoh now that Pharaoh has finally obeyed and sent Israel away. But God isn't done with Pharaoh yet. He hardens his heart (Exodus 14:8) so that he will pursue Israel and be destroyed at the Red Sea.
So the people of Israel are trapped at the shore of the sea, they have nowhere to go. God is essentially using them to bait the trap He has set for Pharaoh, and they are terrified. They know that Pharaoh is coming to destroy them. And Moses tells them, "stand still and see the salvation of Jehovah" (Exodus 14:10–14).
Notice that Moses hasn't once described the deliverance of Israel as "salvation" before this. He hasn't called the plagues on Egypt salvation. He hasn't called them sheltering behind the lamb's blood salvation. He hasn't even called their being sent away from Egypt salvation. It's only now, when God is about to destroy Pharaoh that Moses starts talking about salvation.
And we know how the story ends. God tells Moses to stretch his staff over the sea (Exodus 14:15–18), and He parts the sea so that the children of Israel can walk through it on dry ground (Exodus 14:16). And God hardens Pharaoh's heart one last time so that the Egyptians drive their chariots into the sea (Exodus 14:17), then He brings the water in the sea back together, drowning all the Egyptians (Exodus 14:26–28).
And then, just to be sure that we understand the lesson, the chapter reiterates what happened, "Thus Jehovah saved Israel that day out of the hand of the Egyptians; and Israel saw the Egyptians dead on the sea-shore" (Exodus 14:30). That is a working definition of salvation: it's seeing the enemy dead on the shore.
The children of Israel were redeemed in Egypt. They were led by God into the wilderness. They crossed the sea on dry land, by the power of God. But they weren't saved until they saw the Egyptians lying dead on the shore.
1 Corinthians 10:2 describes the crossing of the Red Sea as baptism. This is one of the reasons I keep insisting that baptism saves. It doesn't regenerate, redeem, justify, or reconcile. But it saves. The connection between baptism and salvation isn't an accident, and it's not made lightly. And notice, it's very much the same idea in 1 Peter 3:20–21.
I am sure that the Old Testament saints were born again. After all, "Abraham, Isaac, Jacob, and all the prophets" will be in the kingdom of God (Luke 13:28), and Christ Himself assures us that new birth is necessary for a man to enter the kingdom of God (John 3:1–7). And scripture is explicit that Abraham was justified by faith alone (Romans 4:1–5). David, too, being justified by faith alone, is a man "to whom God will not at all reckon sin" (Romans 4:6–8). These are all Old Testament truths.
But the Old Testament saints were not united to Christ. This is one blessing we have and they didn't have. We are united to Christ in His death, His burial, and His resurrection (Romans 6:1–5; Colossians 3:1–4). And notice Romans 6 connects our union with Christ to baptism. It's entirely scriptural to say that one huge difference between the Old Testament saints and the New is that we are now baptized into Christ Jesus.
There's a lot more to talk about here, so I'll save that for another time. But let's make this final point: being saved means seeing the enemies lying dead on the shore. I'm almost fifty years old, and in that time, I've heard many, many gospel messages. I've heard many, many evangelical talks. But I have very rarely heard about the dead enemies on the shore.
It's like we're content to be redeemed, and don't really want all that God has for us: not merely justification, but salvation.