On Thursday, Pope Francis stood on the balcony of the Capitol building and spoke through an interpreter to the crowds on the lawn. “I ask you all, please, to pray for me,” Francis said, “and if there are among you any who do not believe or cannot pray, I ask you please to send good wishes my way.” These words made the New York Times “Quotation of the Day” on Friday, and many people resonated because they have said similar things themselves.

Almost daily, my own social media feeds have posts by evangelical friends requesting prayer in much the same way: “Asking for prayers/happy thoughts for my dad’s surgery on Tuesday,” or, “If you pray, please pray for my job interview tomorrow. If you don’t, send good vibes!”

These caveats offer ways to include non-Christians in life events. People want to acknowledge that they feel loved and encouraged by those who share their burdens, if not their faith. And, as Christians, we can—and should—welcome with thanksgiving their affection and concern.

We communicate that happy thoughts are a legitimate alternative to prayer. We incidentally equate the two. I doubt most of us would be satisfied if the boss chose to pay us in Monopoly money or the waitress delivered plates of plastic play food to our table. This kind of indifference—prayer or good wishes, take your pick—denies before our unbelieving friends the Bible’s rich teaching on what prayer really is.

Prayer is not a magic incantation or the smoke gone up from blown-out birthday candles. Prayer is substantive and effective and absolutely necessary.

Prayer is real communication between needy people and their living, loving, listening God. Prayer is, as the catechism of my church says, “an offering up of our desires unto God for things agreeable to his will.” Prayer is as desperate—and as confident!—as my thirsty children asking me for a drink.

We invite people to pray for us because we believe with our whole hearts that God must do what we cannot.

And he does. By the prayers of his people, God sends revival (2 Chron. 7:13-14). By prayer, he grants healing and salvation and better gifts than we could imagine (James 5:14-15; Eph. 3:20). And, by prayer, Satan and his kingdom are beaten back (Rev. 8:3, 5; Eph. 6:18). In the words of T. F. Torrance, “the prayers of the saints and the fire of God move the whole course of the world.”

The Bible does not offer us any spiritual placebo effect, by which a sugar tablet of good wishes just might have the same effect as the penicillin of prayer. Prayer is the thing that weak, sick, anxious, sinful, needy Christians must have. Do not substitute.

In one important way, though, Francis is right. The world fundamentally is made up of two groups of people: those who pray and those who don’t.

In the Christian classic Knowing God, J. I. Packer writes, “People who know their God are before anything else people who pray.” The kind of “knowing” Packer has in view is the mutual knowledge of relationship. In prayer, we humbly reveal ourselves to God—our sins, our needs, our desires—and, in prayer, we lovingly embrace his revelation of himself in Christ.

Prayer is always an activity of relationship. People who know God, pray. And, as Francis and my Facebook friends rightly understand, people who don’t know God, don’t.

Most tragically, by accepting happy thoughts as a decent substitute for prayer, we deny our unbelieving friends a chance to have a relationship with God. We deny them the gospel of Christ.

People were made to talk to God. The Creator set Adam and Eve in the newborn world, and he spoke with them. But then, with a snap of teeth, sin and guilt made the human race both deaf and mute, cutting us off from communication with God. Sinful people cannot speak to a holy God (Hab. 1:13).

And no amount of happy thoughts can make up for the lack of it.

One of the great glories of the gospel is that it restores our right, our privilege, our ability to pray. When Christ died on the cross, he died so our sins would be forgiven. He died so we would be united to him in his righteousness. And he died so we could again talk to God.

As Jen Pollock Michel writes in Teach Us to Want:

Jesus our advocate, brother and friend intercedes on our behalf. It is by the blood of Jesus Christ that we pray and are heard, and it is in the righteous name of Jesus Christ that we find the confidence to believe our prayers are heeded by the Ancient of Days, who has judged our sin through Christ and allowed him to bear on his shoulders “the chastisement that brought us peace” (Isa. 53:5).

My unbelieving friends may be content with warm wishes and good vibes, but I am not. I want them to have communion with the Father, boldly, with confidence, in the blood of Christ. I want them to pray.

I’ll be speaking at a conference on Saturday. If you pray, please ask God to help me. If you don’t pray, please believe in Christ so that you can.

Megan Hill is the author of Praying Together, which will be released by Crossway in April 2016.