Go one level deeper into Pentecostal culture—beneath the worship services and leadership style—and you find a more important and pervasive way that the movement is "Pentecostalizing" world Christianity.

In the 1990s, as a new graduate student, I attended several meetings of the Society for Pentecostal Studies. Organizers set aside time during these conferences for worship and testimonies, and at one such gathering, attendees came to the microphone to describe what the Pentecostal experience of baptism in the Holy Spirit had meant to them.

Until that moment, I had been dutifully following scholarly debates about whether baptism in the Holy Spirit was primarily about holiness or power. But these testifying scholars described Spirit baptism in terms of something deeper than either one. Indeed, they all put their finger on one main effect: a new, joyous sense of communion with a loving God who counted every hair on their heads and watched over them every minute. The central moment of their Pentecostal experience had opened them to a deep well of living water from which everything else flowed; it had opened them to the personal, relational presence of the Living God.

Though it may discomfit the religiously buttoned-down, the rationalists, and the nominal, the Pentecostal God deigns to meet with us and care for us in immediate, experiential ways. We speak to him in a language of love, saying "Abba, Father," and he responds in kind.

This encounter has always been the open secret of Pentecostal spirituality. The belief in God's real, experienced care and the passion for union with Christ—often likened to the thirst of the psalmist's deer for the stream—may turn out to be Pentecostalism's chief contributions to Christianity.