Final answer:
Political parties that jeopardize religion and communal unity are not allowed to be registered because they can fragment the country and disrupt national unity.
Step-by-step explanation:
The reason why political parties that jeopardize religion and communal unity are not allowed to be registered is because they can potentially fragment the country. When a political party promotes sectarianism or discrimination based on religion, it can lead to divisions and conflicts within society, which can be harmful to national unity and stability. Governments aim to protect religious freedom and maintain communal harmony by preventing political parties that threaten these principles.