About 10 years ago, Pastor Rick Warren made a long list of the "up-and-coming" pastors in America he wanted to pray for.

Just as he had older mentors who prayed for him when he started Saddleback Church in southern California at 25 years of age, he felt compelled to do the same for the younger generation of pastors.

Unfortunately, about half the people he listed are no longer in ministry today.

"They burned out; they flamed out morally; they got tired; they got discouraged; they quit," Warren said Tuesday to thousands of pastors and ministry leaders.

"You don't get credit for starting the race. You get credit for ending it well," he stressed. "The only way you're going to finish well is if you build roots, not fads, not therapies, not management."

The Purpose Driven pastor is committed, he said, and is giving all his life to help the next generation finish well. As part of his effort, he is taking them back to the root of the Christian faith and of the church.

"Radicalis", a Latin term meaning "of roots", is serving as his banner.

Warren, who has been training pastors for 30 years, believes most churches, pastors and Christian leaders are "spiritually rootless". While they chase the latest fad, methodology or technology, many are not rooting themselves deep in Christ, Scripture and love. And without deep roots, Christ followers give up ministry as soon as life gets hard.

"How do you know when somebody's got roots, when a church has a root? Fruit," the renowned Saddleback pastor said at the start of the four-day "Radicalis: For Radicals Only" conference. "The evidence of roots is fruits. And the fruit is not just for a season ... it comes back every year."

Warren brought together a line-up of well-known pastors, including Andy Stanley, Perry Noble and Mark Driscoll, to speak to fellow leaders on building spiritual roots in eight different areas of their lives, beginning with radical devotion.

"There's a lot of things I can teach you about how to build small groups – we've got over 4,000 of them," Warren said. "There's a lot of things I can teach you about how to baptise and bring unbelievers in – this year we baptised 2,800 new believers. There's a lot of things I can teach you about how to send people overseas in mission – we've sent over 8,000 people.

"I can teach you those things. But you've got to start in the heart," he stressed. "And you've got to start with radical devotion."

The first purpose in life, he underscored, is worship. That is, to love God more and know Him better.

"At the end of the day it doesn't matter how many things have gone wrong ... how many failures ... if at the end of the day you love Him more and know Him better that day was a success," the southern California pastor pointed out.

"On the other hand, it doesn't matter how many things you've accomplished ... at the end of the day if you don't know God better and love Him more you just wasted your day because God didn't put you on earth to mark things off your to-do list."

Noble, senior pastor of NewSpring Church in South Carolina, offered pastors his own take on radical devotion, saying it begins with an "accurate view of Jesus".

"I don't think we would speak to Jesus the way that we speak to Jesus sometimes if we just understood who he was," Noble stated.

"Jesus, I'm over my head!" said Noble as he humorously demonstrated a likely usual pastor meltdown scenario.

"I know," the SC pastor said, as he responded as Jesus.

"Lord God, I'm so powerless!" he continued.

"Duh."

"God, I don't know what to do!"

"I know. That's why I called you."

Driving his point, Noble said, "I think before we can discover what God wants, we've got to see who He is. The church is so obsessed with what He wants that we've forgotten to pay attention to who He is because I believe when we discover who He is our hearts will beat for the same things that His heart beats for and we will understand what He wants us to do."

Calling pastors to action, Noble alluded to Jesus' command to Apostle Paul: "I did not show you who I am so you can get involved in a Bible study for the next 30 years and discuss insignificant theological topics that will never be settled on this side of Heaven.

"Get up and stand on your feet ... I'm calling you, Paul, to take action because there's a lost and dying world that don't know who I am!"

Noble lamented the reality that many ministers leave their flock when the personal cost becomes too high. But he recalled what Jesus told Paul. "You're going to witness for me; you're going to serve me; it's gonna hurt," he paraphrased.

"The attitude we've got to develop in us is hell will not revoke the calling that He has placed on my life!" he exclaimed. "I will pay the price because I will never be asked to pay the price that he (Jesus) paid for me. So anything I'm going to suffer is less than what he suffered. Jesus, let's do this thing!"

"Radicalis" kicked off Tuesday at Saddleback Church in Lake Forest, California. Attendees recited a prayer and a declaration of allegiance to God that Warren composed and will make available online for Christians to sign. The prayer affirms one's commitment to "being a radical in the truest sense of the word: rooted in Christ, rooted in his love, rooted in the Word".