The blood of Christ cleanses from all sin—it is our atonement. But first of all, it is our security. It is God's way of securing to himself a people ready for a full deliverance. Remember, on the night of the Passover the Israelites were safe but not yet delivered. They still had to face a Red Sea, a wilderness, warfare with giants, imposing walls, and enemy strongholds.
I am convinced that before I can do battle against principalities and powers, before I can resist lust and temptation (our modern giants), I must have the knowledge that under the blood I am secure! Though I am not yet fully delivered, I am out of judgment. The fleshly enemies loom ahead, but the blood has made me a safe soldier.
You cannot fight giants, pull down strongholds, or stand against overwhelming odds unless there is an assurance of absolute security under the blood. No matter what my heart says, no matter how guilty or condemned I feel, no matter what whispering voices I hear, I must know, beyond a shadow of doubt, that I am safe! I am not going to judgment, because the blood on the door of my heart secures me in his sight.
We are always questioning our safety. If God based our security on our love for him or on personal goodness, we would be in more danger than those who broke the Law, for under grace there is a higher claim. God must take security out of our hands so that it stands on his pure mercy and grace alone. Not our devotion, our obedience, or our goodness—but only on his mercy. Obedience and devotion are the results of our love for Christ.
It was not the unleavened bread that saved the children of Israel, but the blood. Not one Israelite moved "in and out" of safety because of some personal fault. They were all safe until judgment had passed. Obedience was to apply the blood to the doorpost. We are called to confess and trust Christ’s redeeming blood.
God never intended for his children to live in fear, with anxiety or guilt. He prepared a rest for them, the perfect, absolute security of the blood of his own dear Son. By his gracious act, God was saying to Israel, "Now that you see I have secured you and removed you from fear of judgment, let Me deliver you bodily. I secured you to make you holy."
The inalterable fact is, not one thing can be added to Christ’s blood to make us more secure! The blood perfectly shelters us, makes us acceptable to God, and saves us from wrath. The apostle Paul states, “Much more then, being now justified by his blood, we shall be saved from wrath through him” (Romans 5:9).