In his book, "Scandalous", scholar Don Carson reflects on the blessings purchased for us by Christ's blood, and the foolishness of our desire to justify ourselves before God.

“All Christian blessings and resources are grounded in the blood of the Lamb. From a Christian perspective, all the blessings and resources that are ours in Christ are grounded in the blood of the Lamb; they are secured by Jesus’ death and resurrection.

Do you find yourself accepted before this holy God? If so, it is because of the blood of the Lamb. Have you received the blessed Holy Spirit? He has been poured out because of the blood of the Lamb. Do you have the prospect of consummated eternal life in glory? It was secured by the blood of the Lamb. Are you in the fellowship of saints, brothers and sisters who love Christ, the church of the living God, a new body, the body of Christ on earth? This is bought, secured, and constituted by the blood of the Lamb. Are you grateful for the spiritual armaments that Paul tells us to deploy (Ephesians 6)? The entire arsenal is at our disposal because of the blood of the Lamb. May we go to God in prayer? It is because of the blood of the Lamb. Do we find our wills strengthened by the Spirit? That incalculable benefit was secured by the blood of the Lamb.

Every whiff of victory over the principalities and powers of this dark age has been secured by the blood of the Lamb.

Picture two Jews with the remarkable names of Smith and Jones. They live in the land of Goshen almost a millennium and a half before Christ. It is early evening, and they are talking to each other near the end of the ten plagues. Mr. Smith says to Mr. Jones, “Mr. Jones, have you daubed the two doorposts and the lintel with the blood of the lamb tonight?”

Mr. Jones replies, “Oh, yes, I certainly have. You heard what Moses said. The angel of death is passing through the land. Some of the plagues have afflicted just the Egyptians, but some of them have been over the whole land. Moses insisted that this plague was going to run throughout the entire land of Goshen where we live, as well as the rest of Egypt. The firstborn of people and of cattle are going to be killed. The only exceptions are in those homes that have been daubed with lamb’s blood, the way Moses prescribed.” He pauses and then adds, “I’m really excited about this because this means that our redemption is drawing near. Of course, I’ve slaughtered the lamb. My friends and relatives are all here, and we’re ready to go. I’ve daubed the blood of the lamb on the two doorposts and on the lintel. How about you, Mr. Smith?”

Mr. Smith replies, “Well, of course, I’ve done the same thing. But boy, am I worried. Have you seen the things that have gone on around here the last few months? Frogs, lice, hail, death. Now Moses is talking about every firstborn. Look, I’ve got only one son; you’ve got three. I love my Charlie, and I don’t want to lose him. I’m scared witless. There’s not going to be any sleep for me tonight.”

Rather surprised, Mr. Jones replies, “What are you worried about? God himself has promised through his servant Moses that if you daub the blood on the two doorposts and on the lintel, you are saved. Your child will be saved. Charlie will be here tomorrow morning. You’ve already put the blood on the two doorposts and on the lintel.”

Mr. Smith replies, “Well, you’ve got that last bit right. I’ve certainly done that, but I’m scared witless just the same.”

That night the angel of death passes through the land. Who loses his son? Mr. Smith or Mr. Jones?

The answer, of course, is neither-because the promise was based not on the intensity of their faith nor on the joy of their obedience but on whether they hid under the blood of the lamb.

Let’s come at this another way. Do you ever have a day that runs something like this? You get up in the morning; it is drizzly and hot, and the air conditioner is broken. You reach for a clean, fresh pair of socks, and you can’t find two that match. You stub your toe on that nail sticking out of the wall that you knew you should have fixed about three years ago. You cut yourself while you are shaving. You stumble down to breakfast, and that day your wife is going out for a special meeting with her friends and has not done anything. You go out to the car, put your key in the ignition, and it will not start. You knew that you should have had the battery checked, and it is deader than a dodo. You get to work late, and people are saying rude things about you. Then your boss says, “Have you finished that report yet? You’re staying late tonight if you haven’t.” The whole day unfolds in one endless set of mini-irritants.

You have an opportunity to speak to some non-Christian friends-a neighbor, someone over the back fence, someone at the gas station-and you are already in such a sour frame that when they ask some dumb question about religion, you answer with a kind of curtness and condescending wit that leaves them shriveled up in a pile of embarrassment. You feel guilty, but you have done it now. Eventually you return home, and your wife has cooked this disgusting stew that your children like and that you detest. You cannot be civil to her, and she cannot be civil to you. The kids that night are really not behaving particularly well. Your wife want you to do jobs, and you want to watch football.

Finally it is time for bed at the end of this long day, and your prayer runs something like this: “Dear God, this has been a rotten day. I’m not very proud of myself; I’m frankly ashamed. But I really don’t have anything to say. I’m sorry I have not done better. Forgive my sin. Bless everybody in the world. Your will be done. In Jesus’ name, Amen.”

But then a few days later you wake up to find the air is refreshingly cool. The sun is shining, the windows are open, the fresh air is wafting through the screen, and you hear the birds singing. You smell something delightful: “Bacon! I can’t believe it! I wonder what the celebration is.” You get up and reach for clean socks and feel full of energy. You’re whistling as you wash in the bathroom and then have a wonderful quiet time with your spouse. You eat a hearty breakfast and then go out to your car, put the key in the ignition, and VROOM!-the car starts right up and takes off. You get to work early. Everybody commends your industriousness and intelligence in the way you discharge your duties. Your boss says, “Wonderful to see you today! Did I tell you that you are going to get a raise? You did such a great job on that contract.”

Now you come across that same person at the gas station, and wonder of wonders the poor brute actually asks another question. This time, however, you respond with wisdom, tact, gentleness, understanding, courtesy, insight, and kindness. Lo and behold, he promises to come to church with you this coming Sunday. Then you arrive home and there is a joyous family dinner. The kids are behaving, and you have intimate conversation with your wife while the two of you clean up the kitchen.

Finally, at the end of that day you get down to pray, and your prayer goes something like this: “Eternal and matchless God, we bow in your glorious presence with brokenness and gratitude. We bless you that in your infinite mercies and great grace you have poured favor upon us. We are not worthy of the least of your mercies … ” And now you go on and on and on in flowery theological language. You thank God for all the things in the day, and then you pray for missionaries and their children and first cousins twice removed. Then you start praying for everyone you can think of in your church, and then you meditate on all the names of Christ that you can think of in Scripture. An hour goes by, and you go to bed and instantly fall asleep. Indeed, you go to sleep-justified.

On which of these two occasions have you fallen into the dreadful trap of paganism? God help us: the sad reality is that both approaches to God are abominations. How dare you approach the mercy-seat of God on the basis of what kind of day you had, as if that were the basis for our entrance into the presence of the sovereign and holy God? No wonder we cannot beat the Devil. This is works theology. It has nothing to do with grace and the exclusive sufficiency of Christ. Nothing.

Do you not understand that we overcome the accuser on the ground of the blood of Christ? Nothing more, nothing less. That is how we win. It is the only way we win. This is the only ground of our acceptance before God. That is why we can never get very far from the cross without distorting something fundamental, not only in doctrine but in elementary discipleship, faithful perseverance, obedience, and spiritual warfare against the enemy of our souls. If you drift far from the cross, you are done. You are defeated. We overcome the accuser of our brothers and sisters, we overcome our consciences, we overcome our bad tempers, we overcome our defeats, we overcome our lusts, we overcome our fears, we overcome our pettiness on the basis of the blood of the Lamb. We dare to approach a holy God praying in Jesus’ name, appealing to the blood of the Lamb.”

Quoted from: Carson, D. A. 2010. Scandalous: the cross and resurrection of Jesus. Wheaton, Ill: Crossway. pp. 100-103