How can one respond to those who refuse to apply the rulings of Islam in the state today, arguing that they do not grant full freedom to non-Muslim citizens, such as the impermissibility of a non-Muslim ruler running for elections and the shedding of the apostate's blood? And what is the wisdom behind that?

The topic of applying Islamic Sharia rulings to non-Muslims in a Muslim society was previously addressed in Fatwa No. 129835 and the references therein. The two questions you asked about were also previously addressed. For the first, please refer to Fatwas No. 116649 and No. 121660. For the second, please refer to Fatwa No. 122412.