Once upon a time, there was a guy named Abraham. He was really old and afraid that he’d die without an heir. But then God gave him a promise: his descendants would be as numerous as the stars in the sky and the sand on the seashore. A couple of decades later, Abraham’s son is born–the firstfruits of a great promise.

And then God tells Abraham to do something unthinkable. He is to take his son up on a mountain and sacrifice him to the Lord. We know how the story ends: Abraham goes up to the altar, the Lord stays his hand, a ram gets the knife instead (see Genesis 22).

Atheists like to use this passage as evidence of God’s cruelty, even though Abraham kept his child in the end. But I think this scripture is indicative of something else–of what it means to be, as Romans 12:1 says, a living sacrifice.

See, there comes a point in a Christian’s life–sometime long after the initial surrender of the sinner’s prayer–where God will really begin to test the believer’s faithfulness. Just when we think we’ve got it all together…when we’ve put aside of all the “big” sins…when we’re pursuing the promise of His destiny…God will call us to the altar of sacrifice. He will ask us to put our whole selves on it, both the good and the bad. And make no mistake, the altar is not a pleasant place to be. It’s uncomfortable. It’s a place of pain and blood-letting. It’s where our flesh goes to die so that the spirit within us may be transformed.

The flesh would prefer to keep on living. It will fight to stay off that altar.

Some of us have heard this sermon before. But now I’m thinking about it in a new way. See, many people–both Christians and non-Christians–assume that the altar is only a place of death…that whatever God asks us to put upon it will be destroyed. Not so. Abraham put his son on the altar and got him back. God wants to preserve the good things within us–the things that are from Him. But, as C. S. Lewis writes, He wants to know that He has all of us. God made us, gave us our talents and personalities, and sent Jesus to die for our redemption. He’s not satisfied with our surrender of just a few flaws. He can fix those flaws, but that’s not what He wants to do. He doesn’t want to improve our humanity. He wants to turn us into new creatures entirely–creatures that are simultaneously more like Christ and more like the people we were originally intended to be.

In a way, that’s a comforting thought–to know that I can place things like my creativity and intelligence into His hands and watch Him transform them into something really extraordinary…something beyond what I could accomplish on my own. Meanwhile, He keeps pointing out the things that do need to die so I can be totally free of my sinful identity: inborn tendencies and desires at the core of my fallen nature. Things that require some extensive spiritual surgery to get out.

Modern Christians, including myself, talk big about grace. It’s a message that’s been sorely lacking in many evangelical circles: “Don’t worry if you’re struggling; God’s grace will cover you.” It’s true. I believe it with my whole heart. But I also believe that this concept of grace is sometimes used as an excuse for avoiding the altar of sacrifice. Some Christians fear putting their whole selves on that altar because they know God might reveal a comfortable habit or weakness that He intends to remove. What they don’t realize is that God also intends to return the good things within them–purified, enlarged, and with all the marks of His glory.

Romans 12 calls becoming this “living sacrifice” our “reasonable act of worship.” Reasonable, because He made us and loves us. Reasonable, because He grants us eternal life over death. Reasonable, because it’s a paltry price to pay in light of Christ’s sacrifice for our redemption. Reasonable, because we get something better in return for our surrender. Reasonable, because that’s the whole point of following Him in the first place. An unbelieving world won’t see it as reasonable, though. On the outside, it looks like madness.

And the truth is, climbing up on that altar is not just a one-time thing. It’s a daily decision. And when you get out of bed in the morning and face that wretched, blood-splattered place, you might be tempted to run away. Think carefully before you do. Because though you may arrive on your hands and knees, you’ll eventually leave on wings…a new creature full of His glory and promise.