What Is the Flesh in the Bible?

If you’ve spent any time reading the New Testament, especially the letters of Paul, you’ve probably run into the word flesh used in a way that seems strange. Paul isn’t talking about skin and bones. He’s talking about something inside every one of us — something that fights against God, fights against our better judgment, and honestly, wins more often than we’d like to admit.

This is the first post in a new series called Flesh vs. Spirit. Over the next eight weeks we’re going to look honestly at the war that every Christian lives with every single day — not the demonic warfare we covered in our last series, but the battle that happens inside you. Before we can talk about winning that war, we need to understand what we’re actually fighting. So let’s start here: what does the Bible mean when it uses the word flesh?

It Doesn’t Mean Your Physical Body

The first thing to clear up is what the flesh is not. When Paul uses the word flesh in his letters, he is almost never talking about your physical body — your arms, your legs, your skin. Your body isn’t evil. God made it. He called it good. Jesus himself took on a physical human body, and that didn’t make him sinful.

The word Paul uses in the original Greek language of the New Testament is sarx (pronounced “sarks”). It’s a word that can simply mean physical flesh — like meat on a bone. But Paul takes that word and uses it to describe something much deeper. He uses sarx to describe the part of us that is bent toward sin. The part that wants what it wants, when it wants it, regardless of what God says about it. Theologians have a fancy term for it — the sin nature. But let’s just call it what it is: the old you. The version of you that existed before Christ, and the version that still shows up uninvited even after you’ve given your life to him.

Where Did It Come From?

To understand the flesh, you have to go back to the beginning. When Adam and Eve chose to disobey God in the Garden of Eden, something broke in the human race. Not just in them — in all of us. Every person born after that moment entered the world already leaning away from God. Already wired to put self first. Already carrying the instinct to do things our way instead of his way.

That’s not an excuse for sin. It’s an explanation of why sin feels so natural. The flesh isn’t something that happens to bad people. It’s something every single human being was born with, including you, including me, and including every pastor, deacon, and Bible teacher you’ve ever respected.

Salvation changes your eternity instantly. But the battle with the flesh does not disappear overnight.

Paul Said It Out Loud

One of the most honest passages in the entire Bible is Romans 7:15, where the Apostle Paul — a man who wrote half the New Testament, planted churches across the known world, and was willing to die for Jesus — says this:

“I don’t really understand myself, for I want to do what is right, but I don’t do it. Instead, I do what I hate.” — Romans 7:15 (NLT)

Read that again. Paul is describing the exact same frustration you feel when you promised yourself you wouldn’t lose your temper again, and then you did. When you committed to being more patient with your kids, and then you weren’t. When you knew what the right thing to do was, and you did the opposite anyway.

That’s the flesh. And Paul wasn’t ashamed to admit it was still fighting him. Neither should we be.

I’ll be honest — I know this battle personally. Like Paul, I find myself doing things I don’t want to do and leaving undone the things I know I should. If you’ve been a Christian for five minutes or fifty years, you know exactly what I’m talking about.

Even Paul wrestled with the battle inside. Romans 7 reminds us that the struggle is real—but grace is bigger.

What the Flesh Actually Does

A few chapters later, Paul gets specific. In Galatians 5:19-21, he lists what the flesh produces when it’s running the show — things like sexual immorality, anger, jealousy, selfishness, division, and envy. That’s not an ancient list. That’s Tuesday.

But it goes even deeper than behavior. Romans 8:7 says that “the sinful nature is always hostile to God. It never did obey God’s laws, and it never will.” (NLT)

The flesh isn’t just the part of you that makes bad choices. It’s the part of you that is fundamentally opposed to God’s authority over your life. It doesn’t want to submit. It doesn’t want to surrender. It wants to be in charge. That’s why doing the right thing can feel like swimming upstream even for someone who genuinely loves Jesus.

The Flesh Doesn’t Leave When You Get Saved

Here’s the part that surprises a lot of new believers — and if nobody has told you this yet, I want to tell you now so you don’t feel blindsided.

When you give your life to Christ, God forgives every sin you’ve ever committed. His Spirit comes to live inside you. You are genuinely changed. But the flesh doesn’t pack its bags and leave. It’s still there. It will be there until the day you die or Jesus returns — whichever comes first.

That’s not a discouraging truth. It’s a necessary one. Paul says in Galatians 5:17, “The sinful nature wants to do evil, which is just the opposite of what the Spirit wants. And the Spirit gives us desires that are the opposite of what the sinful nature desires. These two forces are constantly fighting each other.” (NLT)

Two forces. Constantly fighting. Inside every believer. That’s not a sign that something went wrong with your salvation. That’s actually a sign that something went right. Before Christ, the flesh had no real opposition in your life. Now it does. The fight you feel is proof the Spirit is in you.

The Christian life is not the absence of struggle. The battle itself is evidence that God is working in you.

So What Do We Do With This?

We’ll spend the next several weeks working through specific battles — pride, anger, fear, lust, jealousy, and more. But the foundation for all of it starts right here: you have to know what you’re dealing with.

The flesh is not the devil making you do it. The flesh is not your circumstances or your upbringing, though those things matter. The flesh is the part of you that is still pulling toward the old life. Knowing that changes how you fight. You can’t cast out the flesh. You can’t pray it away. But by the power of the Holy Spirit, you can learn to starve it — and that’s exactly what this series is about.

Romans 8:5-6 gives us the direction: “Those who are dominated by the sinful nature think about sinful things, but those who are controlled by the Holy Spirit think about things that please the Spirit. So letting your sinful nature control your mind leads to death. But letting the Spirit control your mind leads to life and peace.” (NLT)

Life and peace. That’s what’s on the other side of this fight. And it’s worth fighting for.

Next up in the series: What is the Spirit? We’ll look at who the Holy Spirit actually is, what he does inside a believer, and why he is the only power strong enough to win this war.

If you missed our last series on Angels, Satan and Demons, that’s a great place to start. You can find it here: Angels, Satan and Demons

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