Secularism, that is, state-neutrality towards religion, should always be maintained, without question. In countries with a state religion where religious law serves as a basis for the entire legal system, what ends up happening is that religion is exploited as a tool to gain and hold political power, and exercise control over others. As mentioned by another redditor, religion and religious institutions become subservient to the state, and you see it in places like Saudi Arabia, Iran, Egypt, and Pakistan. It’s no coincidence that people like Ibn Sina and Ibn Rushd (also known as “The Father of Secularism”) and some of the great Muslim theologians, philosophers, scientists and thinkers who flourished in the golden age of Islam were secularists. If society is to truly advance, freedom must be granted to all, including religious freedom. And the only place where that can happen is a truly secular state.