We get in Exod. 15 the deliverance founded on chapter 12; and God takes, as to His dealings, an entirely new character.
In chapter 12 He was a judge, acting in that character, and He is met by the blood. He does not meet the sin; the blood meets the judgment, and He passes over; but the people are left in Egypt, safe from judgment. That is not all that God does; it is the foundation of all blessing, but they had not gotten actual deliverance yet. There is not only the value of what Christ has done meeting the eye of God, but He is active in delivering us and bringing us out.
Christ went down to the condition we were in, and by the grace of God tasted "death for everything." He came into death where Satan's power was. He could not be holden of it, but in coming down He put away the sin. He came down in the power of divine life—He was God Himself—and He not only put away sin, though He did that in order to deliver us, for it could not be done righteously if the sin had not been put away; but now He is up out of it sitting at God's right hand in glory, and the worth of His work is such that it sets man in His Person, but as our Forerunner, in the glory of God. There is complete deliverance for us.
God was a judge in chapter 12. Here in chapter 15 He is a deliverer in virtue of that blood.
The Israelites got to the Red Sea and found they could not go any further, and that is very humbling. It is a much more humbling thing to learn you are without strength than that you are a sinner. God says, Trust Me and go forward. God is a deliverer, and there was this much sea that it protected them on the right hand and on the left. The very thing they dreaded, was deliverance to them; they walked through it. We dread death and judgment, but it is through them we are delivered—the death of Christ.
Then they have to go through the wilderness, but they have come to God first. Death is gain, and judgment is gone for the believer.
He guided them in His strength (when they had none) to His holy habitation. "I bare you on eagles' wings, and brought you unto Myself." Then there is peace.
We are brought to God by His power and righteousness, and the life that was manifested in Christ's resurrection from the dead; and from that there is a reckoning on divine strength for the way. Divine power has come in to deliver. Then what is Satan's power? There is perfect present deliverance from Pharaoh and Egypt, and the people are brought to God Himself by God's own strength. Then that work forms the ground for reckoning on God for the rest.
We see in verse 17 that God has an inheritance for His people. We do not have that (the glory) yet; but what we have enables us to reckon on Him for it. He brings us to Himself and now dwells among us, consequent on redemption (see chap. 29:45, 46).
The moment I get there, I say, "Holiness becometh Thine house." You cannot speak of holiness to a person before he is redeemed; he has nothing to do with it except to say he has none. The Lord is "glorious in holiness," and now He has brought a people to Himself and He must have them holy.
In the cleansing of the leper, the blood was to be on the tip of the right ear, on the thumb of the right hand, and on the great toe of the right foot. No thought is to go into our mind, we are to do nothing with our hand, and there is to be nothing in our walk unfit for the blood of Christ.