The growth of the Pentecostal movement is not only marked by the proliferation of the Pentecostal churches in Africa and the diaspora but also by the adaptation to the Pentecostalist practices particularly pneumatic experiences by mainline Christianity known as Pentecostalisation. Instead of completely joining the Pentecostal movement, some mainline churches adjust their practices to suit their congregants who are more pentecostalist and charismatically inclined. This article uses the Evangelical Lutheran Church in Southern Africa, the Devhula Lebowa Circuit, Limpopo province in South Africa as a case study to illustrate that the adaptation to Pentecostalist practices in the church is the source of church growth and ecumenism. This kind of adaptation has some implications in demonstrating that different Christian traditions can learn from one another to grow in terms of numbers. Secondly, it demonstrates that the Christian tradition can move towards unity by learning from one another instead of being divided along denominational lines. Through a participation observation method, this study shows that Pentecostalisation cannot be viewed negatively but should be revisited by scholars considering church growth and the notion of ecumenism.