I am also an atheist. Our country has christian prime ministers in the past. It was not a problem, because virtually all the christians that are left in our country (the majority of people are atheists of agnostics these days) believe in a separation of church and state.

It is not about christianity. Authoritarian and populist leaders will always coopt/corrupt whatever is convenient for them. Christianity, socialism, capitalism, whatever works to rally a substantial portion of the population.