BJP does get the majority of Dalit votes all over India though. It is Muslims who don’t vote for BJP.

Actually, it’s a lot more complicated than that in Kerala. Christians are deeply divided into multiple sectarian groups that started with schism in the Pre-colonial period and increased greatly moving into the colonial period. Historically, the original pre-colonial Christian communities that existed in the state were heavily interrelated with Levantine Christian groups such as the Assyrians, and mainly centered their religious activity around their center of operation in Iraq specifically. 

After the initial migration to India happened around the same time as the Gondhpharid Kardamaka dynasty ruling over Gujarat, as seen in the traditional literature, there were a few other waves. In one of these migrations, a set of Jewish-Christians from southern Mesopotamia led by Thomas of Cana, who settled and gradually developed into the modern sub-Nazarene group called the “Knanaya”. These new groups of Christians conflicted with the old Christians, leading to the North-South Divide between the old and new groups. Eventually, more divisions kept on happening as theological disagreements continued over time. 

When the colonial empires took over the land, they basically Westernized Christianity on the population, and the pre-existing Christian population opposed this imposition. Things became dicey after the portugese “lost” *cough* killed *cough* a major archbishop from the local community in France. Then, the oath at the bend cross took place, where the christian community stated that they will never fully merge into the European churches. 

Then, this created a massive divide between the original “Nazrani” Christian and the later “European” Christian groups. Nazaranis function as the upper caste, and the European-origin churches function as the lower caste since they were more open to external converts. Also, the Knanaya community within Nazaranite community straight ban inter-denominational (*cough*Intercaste*cough*) marriage with the other Nazarine. Then, there are further internal complex hierarchies, where denominations functioned as a caste (specifically Jaati) group. 

Also, Kerala Christians are nothing like Goan Christians. Anecdotally, I was born into an old conservative “Nazrani” family, where one of my great-grandfathers published books on Christian theology, and another was so sectarian he would walk on the other side of the road if he came across someone from another sect. At the same time, one of my great-grandfathers (the road walker) was an ayurvedic physician, and he literally built a family home/Tharavad according to the Vastu Shastra. Another one literally served as a scribe or minister in the royal court of the Poonjar dynasty and was even rewarded with lots of land that kept him rich for generations, until they naturally squandered it.