Point of secularism is to avoid thinking that because some religious book teaches something than it must be right. Cutting a hand for theft or stoning someone is crazy if you don't look it through the eyes of a faithful.
Have you conducted any surveys in Turkey? Please feel free to provide any studies linking religion to happiness. People that are happiest are usually have access to basic things like education, food etc. You can rule out the most of Muslim world based on that :).
And whose interpretation is right? Anyway I am still waiting to see any reasonable and rational reasons, as to why sharia law is the best other than reasons like because Islam said so. Laws should be based on pragmatic and rational thinking not on Islam said so.