Evangelical pastor Rick Warren delivered a lecture in his trademark Hawaiian shirt to 20,000 people at the largest church in the world, Yoido Full Gospel Church in South Korea, on Thursday.

Despite the rainy weather and day of the week, ministers and believers crowded inside the main chapel of the megachurch where the thousands remained seated for the entire Purpose Driven Church Conference to pick up Warren's pastoral method.

After raising Saddleback Church in Lake Forest, Calif., which he heads, into a global church through the 40-Days of Purpose Campaign, Warren has presented a new church growth model to all 50 states in America and 10 countries around the world.

In his first lecture, "Raise a Purpose Driven Church," at this week's conference at Yoido, Warren emphasized that a church must become purpose-driven to grow healthy. He further explained four phases for a revival to occur – personal revival, relational revival, revival with a purpose and structural revival. Among those, many churches get stuck at the third phase – revival with a purpose – and therefore cannot grow.