Banning the sale of liquor during the Vesak* week doesn’t make Sri Lankans any more Buddhist than they already are. It’ll just alter their external behavior. That’s not the goal of religion.
You cannot legislate religion. Law and religion both aim for morality but do so using two completely different approaches. The Law does not care whether a person is good or bad — it’s only concerned with his external behavior. Therefore it can depend on the threat of punishment. Religion IS concerned with whether a person is good or bad, sometimes REGARDLESS of his external behavior. The Law is compulsory. Religion is voluntary. Mix the two and you have a problem.
To say nothing of the wrongness of one religion ruling all in a multi-religious society. The Law MUST be secular. There is NO place in the law for religion-specific or group-specific morals.
* The Buddhist holiday commemorating the birth, enlightenment and death of the Buddha