Are there also fundamentalists among Christians who want to set up a theocracy?
Yes, there are Christian fundamentalists, but not really any who would want to set up a theocracy.
Even if these days it often seems as if fundamentalism was a specific problem for Islam, the term and the phenomenon arose in a Christian context in the 19th and 20th centuries. [...] The fundamentalist problem had its origin first and foremost in the Christian communities of North America which, appealing to the creation narratives in the Bible and who, in radical opposition to Darwin’s theory of evolution, isolated themselves to a large extent from the world around them and from the modern world as such. Fundamentalism is, however, a temptation for all religions and ideologies in as far as they claim to be in possession of the absolute truth. It is quasi the original temptation of the religious person per se who is searching for the final answers. This can be seen from two typical and therefore inevitably generalised forms of Christian fundamentalism.
The typical Protestant variant of a fundamentalist understanding of Christianity says: Something is true because it literally says so in the Bible. The Catholic version of this is that something is true because the Pope said so. The first version is generally called biblicism. The latter can, accordingly, be understood as institutionalism or church positivism. Religious truth and truth per se are then ascribed to a certain tradition, or more precisely, a particular authority. Critical questioning is not possible. This means that criticism and the ability to ask critical questions, i.e. human reason, are not allowed to play a part in the religious and ideological realms. This faith, which in the final analysis is faith in a definite authority, is blind to the influence of reason. It usually occurs in a clearly separated and closed community led by a charismatic leader. Religion thus becomes the separation from the rest of the world and from society. Karsten Kreutzer, art. „Fundamentalismus“ in: A. Franz/W. Baum/K. Kreutzer (Ed.) „Lexikon philosophischer Grundbegriffe der Theologie“. Second edition. Freiburg: Herder, 2007, pp. 150-153.