Jared Brock, author of “A Year of Living Prayerfully”

Today, millions of Americans across the nation will bow their heads in prayer for their country. Having a National Day of Prayer is a tradition that dates back to 1775, and every president since Truman has signed an annual proclamation calling citizens to “turn to God in prayer and meditation.”

But does prayer work?

Is anyone listening?

What, exactly, is prayer?

There are over seven billion people on this planet, and almost every single one of us has prayed at some point in our life — yet prayer remains a huge mystery.

I hadn’t always had a crappy prayer life. When I was in high school, I experienced all sorts of crazy things because of prayer. It all started when our Christian lunch group was kicked out of the school. We went down to the principal’s office to see why, and she told us that religious groups could no longer meet inside. Except the Muslims, Jews, and Buddhists.

So basically, no more Christians inside.

Long story short, some of the parents took the school board to court, and won. We got a free pizza party as an apology, but not before we endured a long winter of meeting outside in the snow. The Salvation Army supplied us with blankets and hot chocolate, and we were on TV and in the local newspaper.

And a crazy thing happened.

Teenagers saw us shivering in the cold – praying for revival – and started to stop in. Pretty soon, dozens of students were embarking on a faith journey. There was a stretch of a few months where someone was being converted every single week. Some of them are church ministers today.

But alas – I grew up, got married, got a job. Life happened, and I forgot about prayer.

Then my wife Michelle and I visited the red light districts of Amsterdam.

We run a charity to fight human trafficking, and we were filming a documentary undercover.  On our first night in Amsterdam, we visited De Wallen, the most famous of the city’s three red-light districts.

The sex behind the district’s closed doors is completely divorced from any ideas we might have about romantic love. After a night in De Wallen, women are left tending to their bruises. It’s the furthest thing I know from the Cinderella story.

In the middle of the red-light district stands the oldest building in Amsterdam—an eight-hundred-year-old church. In the shadow of the belfry, men rent bodies. Every hour on the hour, men abuse women to the soundtrack of church bells.

As I stood in the middle of this scene, I was completely overwhelmed. “God,” I said, “You need to end this. We need to end this. I need power in prayer.”

So I traveled 37,000 miles around the globe on a modern-day pilgrimage. I danced with rabbis, visited monks, walked on coals, toured North Korea, gained an audience with the Pope, ate lunch at the Vatican, and learned a world of prayer lessons across the Judeo-Christian faith tradition.

I wanted to see how the rest of my faith family prays, including some of the weird uncles and cousins. My journey certainly took me to some interesting places – including a prayer mountain at the world’s largest church, a firewalking guru convention, and even a visit to Westboro Baptist Church.

Though a constitutional challenge against the National Day of Prayer was thrown out in 2011, many Americans now wonder if prayer has simply lost its relevance in an age of science and reason. It’s understandable – people in my generation are skeptical about prayer. We see a world in desperate need, but don’t see how many religious activities are helping.

Many people think that God is like Santa Claus – I know I did. We treat God like a spiritual slot machine that gives us what we want, when we want it. I think we’ve missed the point of prayer. Prayer is about relationship – as we spend time with God in prayer for others, we’re compelled to do something on their behalf.

Prayer becomes life’s greatest work.

Jared Brock is the co-founder of Hope for the Sold and the author of A Year of Living Prayerfully.