A combination of social divisions and politics can be really dangerous. A democracy involves competition among various political parties. As their competition tends to divide society, if they start competing in terms of some existing social divisions, then it can convert those social divisions into political divisions, which can lead to conflict, violence and even disintegration of the country. An example of this is the disintegration of Yugoslavia into six independent countries.
However, the combination of social divisions and politics is not always negative. The political expression of social divisions allows marginalised and disadvantaged social groups to express their grievances and ask the government to rectify them. The system of reservation of seats in Indian legislatures for the socially disadvantaged has allowed such social groups to have an adequate representation in the decision making process.