How do pastors prepare to preach? Prayer, reading and an eye on the clock.

Local pastors have hundreds of options when they approach the pulpit. Which scriptures should they turn to? How can they make words written thousands of years ago relevant today? How long a sermon is too long?

Answers to these questions differ among Chattanooga's various churches, just like they do in congregations across the country.

A study released this week by the Pew Research Center sheds light on the different sermon styles of churches across the country, from average length to common words and books cited from the Bible. The analysis included nearly 50,000 sermons shared online this spring by more than 6,400 churches across the United States.

The study found the median sermon is 37 minutes long, though the number varied wildly among Christian denominations - it was 14 minutes for Catholics, 39 minutes for evangelical Protestant churches and 54 minutes for black Protestant churches.

The Rev. Sherry Cothran, St. Marks United Methodist Church lead pastor, said her sermons fall near the middle. Around 20 minutes is the perfect amount of time for her to get a message across without losing listener interest, she said.

The Methodist pastor, like most in the area, often turns to the lectionary, a schedule of Bible verses, for the scripture passage for that Sunday. She then looks at commentaries on the book to learn more information in creating the hook, or lesson, she said.

"You build a story around the text," Cothran said. "Then you work with the hook that brings whatever that good news or that closure is so people have something inspirational, thoughtful or thought-provoking that they can take with them throughout the week."

Bret Sullivan, Covington Theological Seminary president, said seminary students are taught to include prayer in sermon preparation to understand what message God wants them to spread. Pastors too often can rely on what other people have said about a text rather than looking inward for a new perspective, he said.

There is often a lot of important information to convey in a weekly message, which is why Covington students are advised to structure their sermons to last at least 50 minutes, Sullivan said.

"We try to teach our students that you're going to set the tone [at the church]," he said. "You're going to steady the diet, if you will, for your people over time. Over time, you want to build in them a diet where they can take a 50-minute to an [hourlong] message."

READ MORE: The Protestant Bible and Catholic Bible are not the same book. Here's what you need to know about the difference.

Sermons pushing 50 minutes are common at Westside Missionary Baptist Church, said the Rev. Timothy Careathers, senior pastor. Feeding off the energy of the congregation and responding to their reactions to the message can extend the time he is at the lectern, he said.

"In my tradition, the point of preaching isn't just to get a point across," Careathers said. "It's about creating a performance [to inform]."

Careathers, and several other local pastors, said he turns to a network of colleagues throughout the week to discuss sermon ideas or work through particularly tough passages. Many pastors said they work to keep their messages relevant by connecting them to local, state or national current events or thinking about what particular needs are present in their congregations that week.

While each tradition may vary in its length of message, Cothran said all pastors stand in the same position: They are a bridge between ancient words and modern life.

"Every genre has its own beauty," she said. "There's no real right or wrong. That's what we've learned. It's about interpreting the word for the people."