This is my understanding of the Cambodian church from my short time there. I checked it with a close Khmer Christian friend:

The Cambodian church began through French missionaries. While there was some growth of the Cambodian church before the Khmer Rouge, surprisingly, post-Khmer Rouge has seen an exponential growth in the Cambodian church. The main reason for this surprise is that the Khmer Rouge targeted and killed those with an education. This included a lot of church leaders. Since the Khmer Rouge ended (nearly 30 years ago), the then small church has grown rapidly to be now about 3% of the 16 million people living in Buddhist Cambodia. A lot of this growth has come through the Pentecostal denomination. This growth is quick, particularly when you compare it with other countries in the region where the church is not growing as quickly. One possible reason for this growth is the openness that Cambodia has shown to outsiders, given its need for assistance following the civil war. However, with quick growth in the church comes two problems; division and false teaching. One senior leader also sees a real need arising because many Khmer Christians don’t have much sense of what it means to be a committed follower of Jesus.

These are some of the issues that the Cambodian church faces. This is further compounded by the need for educated leadership. Cambodia’s young population (around 50% under the age of 22), combined with the leadership vacuum created by the war, has affected society and the church. Also, the average level of education in Cambodia also provides further challenges for leaders and churches.

To read more about the Khmer rouge, a series I wrote on Cambodia before we left is available here, here, here, here, and here.