Could Israel have crossed the Red Sea by their own ability?
No. Israel had no means to cross the Red Sea by their own strength. They could not construct a pontoon bridge or requisition ships and boats. They had to wait on the power of God, who brought about their redemption by exercising His power.
Les explains that this was a step where God had to bring about Israel's redemption by exercising His power. Israel could not throw up a pontoon bridge or requisition ships and boats to cross the Red Sea; they had to wait on the power of God. He connects this to 1 Corinthians 5:7, where Paul writes that Christ our Passover was sacrificed for us, and to the resurrection as the power that makes salvation possible, otherwise we are yet dead in our sins.