Wimber strongly espoused Kingdom theology, and this approach to the charismatic differed from many of his peers and predecessors. Wimber's embrace of this new approach led a friend, C. Peter Wagner, to coin the phrase, "The Third Wave of the Holy Spirit" to describe the concept he taught. The Third Wave differed from classic Pentecostalism and the Charismatic movement, foremost, in their approach to speaking in tongues. Whereas the previous groups had emphasized the gift of tongues as the only evidence for the baptism of the Holy Spirit, Wimber and those he influenced emphasized that this was just one of the many spiritual gifts available to believers, as taught in the Bible. His teaching revolutionized what was a major theological stumbling block to some mainstream Evangelicals, and normalized the demonstration of "signs and wonders" in current times. Wimber held influence with a number of them, most famously Jack Deere, C. Peter Wagner, and Wayne Grudem.