Apples and Oranges? What Do We Mean When We Use These Words?
I think we confuse redemption, salvation, deliverance, ransom, and other phrases when we engage conversations like this. In other words, the means of salvation is a different discussion than being delivered from slavery. I think this confusion is aided when we believe that the way to salvation for God's people in the OT is different than the way to salvation after the resurrection. If there was a way to salvation in the OT without the necessity of the sacrifice of Christ, the the Cross of Christ loses it's power - even for us today.
We see that God's action, in redeeming Israel from Egypt, did not preclude Israel from turning from God in the future. However, going down this line of thought potentially creates problems for the Calvinism perspective.
NT305 New Testament Theology
First, God’s law was given to an Israel already redeemed. God first called Israel to be His people, brought them out of Egypt, formed them as a people in the wilderness, and then He gave them His law as a way to instruct them in the way they should live as His people before Him. The law was never intended by God, in other words, to be a means of Israel’s salvation, but to secure Israel’s life and prosperity and the land. Deuteronomy has a lot to say about this function of the law.