The Second Reading says that the blood of Christ cleans our consciences from dead works.
Anybody who does laundry can tell you that one of the hardest stains to get out is blood. Why would anybody think you could clean things with blood?
The answer is that it depends on what you are trying to clean. The Second Reading is talking about cleaning dead works out of the conscience.
But what is a dead work?
Well, a thing that is dead just lies there, without moving. So dead works are works that don’t go anywhere. And where would works be going except where the person who does the works wants them to go?
And now we have a better idea of what a dead work is, don’t we? In Romans 7:15, Paul says, “I do not do what I want, but I do what I hate.” Is there anyone who doesn’t understand this problem? Examples of it are easy to come by. Here’s one: you set out bravely to give up smoking, and day after day you smoke.
It’s not hard to see why dead works stain a conscience. Whose conscience would not feel stained by endless daily failure to do what he himself wants to do?
This is what the blood of Christ cleanses us from.
Blood is the life of a thing, scripture says (Deuteronomy 12:23). If in the Eucharist the blood of Christ comes into us, then Christ’s life comes into us too. By his life, we are made into one body with him, one living body, with a living Spirit, the Spirit of Christ.
What we could not do on our own, because our works are dead and our consciences are stained, the blood, the life, the Spirit of Christ can do in us.
When we are united with Christ through his body and blood in the Eucharist, our works live, too, through him. And if our works live, then our consciences are cleansed too.
In fact, it turns out that even our dirty laundry is cleaned by the blood of Christ. The saints in heaven have made their clothes white in the blood of the lamb (Revelation 7:14).
The old Spiritual hymn is right: there is power in the blood!