John Piper opened up about his eight-month leave from ministry last year as he spoke to hundreds of pastors Monday in Phoenix, Ariz.

He revealed a revelation he had during that period when he was re-examining his soul and his ministry efforts and refocusing on his marriage. And that is, the ultimate purpose of all things is to hallow God's name.

"What should be the all-defining, all-shaping, all-controlling desire of our hearts as pastors?" Piper posed at the Southern Baptist Convention's Pastors Conference.

To "live for the hallowing of God's name."

Last year, Piper had taken his first-ever break from ministry. The break was necessary, he announced, as he found "ongoing character flaws" and "several species of pride" within himself. While not at the level of disqualifying him for ministry, the flaws were enough to cause Piper to grieve over them and remove himself from all preaching, writing and speaking for eight months.

On Monday, he told Southern Baptist pastors that he spent a lot of time during that period meditating on the Lord's Prayer and assessing his 40 years of ministry.

"I saw something in the Lord's Prayer I had never seen before," the Minneapolis pastor said.

"I have tried to devote my life – with all my husband failures, father failures, pastor failures, friend failures, any other possible failures I'm sure I've done them – to the God-centeredness of God and my aspiring, yearning to join Him in that activity. God is passionate about hallowing the name of God."

"Since ... it's God's number one passion, I just wanted to get on with that. I want to be there with all my heart," he added.

There is something unique about the first line of the Lord's Prayer, he noted.

"It's the only petition in the prayer that asks God to perform a specific response for the human heart – hallowing, esteeming, treasuring."

Before, Piper had understood the Lord's Prayer as more of an acclamation (i.e. 'Praise you that your name is hallowed') but he realized after 22 years that this was actually a petition and an imperative.

During his leave of absence, Piper wrote in his journal on October 9: "My one great passion, nothing is more clear and unshakeable to me than that the purpose of the universe is the hallowing of God's name."

The following day, he wrote another journal entry, stating, "Lord, grant that I would in all my weaknesses and meditations remain close to the one clear grand theme of my life – your magnificence."

Piper, who grew up in a Southern Baptist church, pleaded with pastors to be radically God-centered pastors by making the hallowing of God's name "the supreme goal of your ministry and the aim of every breath you take."

"He told us to pray for that," he noted.

Recognizing that Southern Baptists have a passion for the Gospel of Jesus Christ and to spread it around the world, Piper noted that valuing supremely the holiness of God is for the sake of the Gospel.

"Jesus Christ ... came into the world to vindicate the infinite worth of God's holiness which had been desecrated by our sin and which seemed ... to be taken lightly because it was being passed over for nothing more than the blood of bulls," he explained.

"Jesus came to set it right," he went on. "He came ... to vindicate the holiness of God."

"In the Gospel, more clearly than anywhere in the universe, God's name was hallowed."

Piper returned to ministry, including the pulpit of Bethlehem Baptist Church, in January.