Any good Protestant will tell you that we are saved by grace alone through faith alone. That is a powerful truth that frees us from the futile cycle of spiritual perfectionism, which is a fruitless attempt to earn our way into God’s favor. We are not saved by the good things we do. We are saved by the grace of God through faith in Jesus Christ. But here’s the question you have to ask yourself: Do I know what faith is? When the New Testament authors used the Greek word pistis to write about faith, are you thinking of faith the same way that they were thinking of pistis? Because if the only thing by which we are saved is faith, then we ought to know exactly what it is. There’s a lot riding on this.

You might be thinking to yourself, “The Bible tells us plainly what faith is: it’s the substance of things hoped for and the evidence of things unseen.” Yes, that’s true. The author of Hebrews talks about faith in these terms. But this is not a definition of the word faith as much as it is a description of faith in a believer’s life. Faith is experienced as the present reality of a hoped-for future based on the resurrection of Jesus Christ. Faith is a life lived in resurrection hope, and in this way, the life of faith is its own proof for the existence – and especially the death, resurrection, and ascension – of Jesus. But you can see that this is a description of Christian faith, not a definition of the apostolic usage of the Greek word pistis.