Is secularism harām? More specifically the kind of secularism espoused by the Cumhuriyet Halk Partisi of Turkey. And is it harām for a Muslim to vote for such a party?

It depends on what is meant by secularism. It would be haram for a Muslim to become a “secularist”, meaning they abandon Islam and support living life according to secular principles.

Muslims should vote for whatever party is most likely to do the most good and the least evil. Personally I would be unwilling to vote for Islamists who believe that they should force Islam on the country for the greater good. If such a party is opposed by a secularist party that truly believes in justice, civil rights and religious freedom, then the secularist party may actually be the more “Islamic” choice. Just because a person or party claims to be Islamic doesn’t mean they will be better for the population than the secularist party. As Muslims we should keep in mind both the interests of Muslims and non-Muslims, and we should never support support a Muslim who dehumanizes non-Muslims and thinks their rights and freedoms should be restricted.

I am not familiar with the party you mention so I cannot comment on it. In my experience most Middle Eastern secularist parties are extremely anti-religious and would happily ban hijabs and demolish mosques if they could get away with it. So just because a party claims to respect democracy, human rights and religious freedom doesn’t mean that they really believe in these principles. We should look at the party’s leaders and their track record. A party leader who claims to respect religious freedom yet has many anti-Islam speeches, or thinks hijabs are ugly and should ideally be banished, should never be trusted to respect religious freedom.

The ideal system of governance in the modern world, as far as I know, is to have a constitution that ensures the rights and freedoms of all citizens, Muslim and non-Muslim. Then there should be an Islamic government within that that only applies to the Muslims. So Islamic laws should never be applied to non-Muslims unless they freely choose it. And Muslims should have the right to leave Islam so that Islamic law would no longer apply to them.

This is the most “Islamic” way for a Muslim population to behave: to respect their non-Muslim and irreligious neighbors and to never want to force anything on them. They should all work in good faith toward a constitutional system that ensures the rights of everyone. And then if Muslims want Islamic law, they should be allowed to have it for themselves.