After the Indonesian Genocide

Unlike the Toba Batak, who embraced Christianity fairly readily, the Karo continued to follow their traditional religion for several decades after the arrival of the first Christian missionaries in the Karolands.

Following the Indonesian Genocide in 1965-1966, at which time over 70% of the Karo still followed traditional religions, there was a push for Indonesians to identify with an established religion. Many Karo joined the GBKP (Batak Karo Protestant church) (60,000 were baptised in 1966-1970.^[4]), and from 5,000 Muslims (mostly non-Karo) in Karoland in 1950, there were 30,000 in 1970.

At this time, the Balai Pustaka Adat Merga Si Lima (BPAMSL) was established in Berastagi. BPAMSL, proclaimed the 'agama Pemena', or the religion (agama) of the founders (Pemena).

The concept of 'religion' was relatively new in the Karoland; historically the neighbouring Muslim people, were known as 'kalak Jawi' or the people of the Jawi lands, and the concept of 'kalak Kristen', or Christian people, was the first time that people were identified by their religion rather than their land. The 'agama Pemena' of BPAMSL was a defence against accusations of atheism, Communism or animism.

BPAMSL conducted a ceremony in the Lau Debuk–Debuk hot spring akin to the one to invest a new Karo village. This ceremony essentially validated the Dutch-established Berastagi as a 'true' Karo village, and was attended by the regent of Karo regency and other political figures.