We’ve been exploring the New Covenant in the last several posts. We’ve seen that we have a better priest, a better propitiation (the spotless sacrifice), and better promises. At the end of the last post, we asked the question, “What do we do with this?” Or, as I used to say to my students, “So what?” Good theology is more than just information to be learned and believed. Good theology is that which helps us encounter God and changes our hearts. So, then, what does the New Covenant really mean for us? We’re going to look at this by asking and answering a few questions.

#1: What is the most basic, fundamental difference between the Old and New Covenants?

The Old and New Covenants have some similarities. They were both instituted by God, not man. They both required a sacrifice, and both were sealed with blood and a covenantal meal. There are many differences between the two covenants, as we have seen in the previous posts. The most basic difference lies in how the covenant people (Israel and the church) relate to the covenant and to God. Under the Old Covenant, the people obeyed (or didn’t obey) God’s law simply because it was the law. The mentality is, “The law says this. . . . I should do this. . . . I’m supposed to do this.”

Fallen human nature has no desire to obey God. In fact, fallen human nature is hostile and opposed to God and His ways. You’ve heard the saying, “I just don’t have it in me . . . “? When it comes to obeying God, fallen humanity just doesn’t have it in us. Obedience is mostly (if not fully) outward.^[1) The New Covenant, however, doesn’t just give us a new way to obey, nor does it just give us a new reason to obey. The New Covenant fundamentally changes the one who trusts in Christ. He or she now has a heart that desires and longs to obey and please God, to know Him and to walk in His ways. This is why Paul can say that if anyone is in Christ, he is a new creation (2 Cor. 5:17). This is the most fundamental difference. The Old Covenant demands obedience but leaves the heart unchanged. The New Covenant changes the heart and then invites obedience.

#2: If the promises of the New Covenant are actual truth (not just theological or positional truth), then why do we still sin?

This is a logical question, and one that’s asked often. Unfortunately, many people assume that since Christians still sin, we must not have been actually changed. But that’s not the case. We have to ask ourselves, “Does God do what He says He will do?” The obvious answer is, “Yes!” He is faithful to keep His promises. When God gave those promises of the New Covenant in Jeremiah and Ezekiel, did He intend to keep them? Of course He did! Remember that Jesus specifically referenced the New Covenant when instituting the Lord’s Supper.

And [Jesus] took bread, and when he had given thanks, he broke it and gave it to them, saying, “This is my body, which is given for you. Do this in remembrance of me.” And likewise the cup after they had eaten, saying, “This cup that is poured out for you is the new covenant in my blood.” (Luke 22:19-20)

Paul certainly speaks of believers as having been changed. Look what he told the Corinthians:

Do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived: neither the sexually immoral, nor idolaters, nor adulterers, nor men who practice homosexuality, nor thieves, nor the greedy, nor drunkards, nor revilers, nor swindlers will inherit the kingdom of God. And such were some of you. But you were washed, you were sanctified, you were justified in the name of the Lord Jesus Christ and by the Spirit of our God. (1 Corinthians 6:9-11, emphasis added).

Notice how Paul speaks of the Corinthians. Now, we need to remember that this was a very troubled church. The whole of 1 Corinthians addresses multiple problems in the church. When we read this passage in context, we see that Paul is saying, “You are acting like the unrighteous! Why are you acting that way, when you’ve been cleansed and changed?” So, the New Covenant, the blood of Christ, does change us.

But back to our question. If that’s the case, why do we Christians still sin? Now, we know that we do sin–unless one believes in sinless perfection, in which case that’s a totally different conversation (and you’ll find the answers here less than satisfying). But why? The short answer is the flesh. In the previous post (“Better Promises, Better Covenant“), we saw that the Lord promised, “I will remove the heart of stone from your flesh and give you a heart of flesh” (Ezek. 36:26). We referred to the heart of stone as the Sinful Heart. The Sinful Heart is totally opposed to God, seeking to live independently of Him and His ways.

The Bible considers the heart the very center, the very core, of our being. And as such, the Sinful Heart thoroughly programs our entire body and being to live independently of God. We learn to do things our own way. We learn that we can arrange our lives to provide our own satisfaction, safety, and significance. There is no part of the human that is untouched by the corruption of the Sinful Heart. This programming, if you will, occurs through the mind. We develop beliefs and images of ourselves, God, the world, and others that reinforce the notion that we must and can live independently of God.^[2]

What happens at the new birth (John 3:3) then? God promised to remove the heart of stone (the Sinful Heart) and replace it with a heart of flesh (the Spiritual Heart). Since we’ve established that God does what He says He will do, we can say that one who is saved has that new, spiritual heart. This heart, instead of being opposed to God, is inclined toward Him, desiring to worship, obey, trust, and please Him. Now, while the heart has been replaced, the old programming in the rest of us has not. The Bible calls this “the flesh.”

I like to use the analogy of the old-style mainframe computers. Back in the early days of computers there would be a mainframe computer (usually the size of a room) connected to other terminals (called “dumb terminals”). The dumb terminals took their programming from the mainframe. So, if someone wanted to infect the terminals with a virus, all that was needed was to introduce the virus into the mainframe. That’s exactly what’s happened withe the Sinful Heart. It has thoroughly programmed us with the virus of sinful independence from God.

Now, even if that mainframe were replaced, the programming in the terminals would remain, so they would need to be reprogrammed through the mainframe. That’s what God has done. He has replaced the Sinful Heart with the Spiritual Heart. But the flesh (the old programming) remains. It’s so interwoven throughout our being that it will take time (a lifetime, actually) to replace it. Remember, that old programming consists of those ideas, beliefs, and images that reinforce our independence from God. Spiritual growth and transformation, then, consists in cooperating with the Holy Spirit as He replaces that old programming. Paul calls this “renewing of the mind” (Rom. 12:2). Notice that there’s nowhere in the New Testament where we are told to have our hearts renewed or changed. That’s because our heart has already been changed.

We’ll pick up with this topic, how we grow spiritually, in our next post.

Continue to Part 2 of the series >>>

Notes

[1] There are many examples of Old Testament believers having the desire to obey God from their heart, and in fact this is what the law requires. Those people had their heart changed like what we have described.

[2] Since this isn’t a post on the theory of the person or biblical counseling, we won’t go deep into this subject. However, it is an important subject both in understanding spiritual formation/discipleship and biblical counseling.