ideologue(n = noun.person) ideologist - an advocate of some ideology;
is a kind of advocate, advocator, exponent, proponent
an adherent to or advocate of some ideology{3}. [WordNet 1.5]
ideologue, n.
1 a theorist; a visionary.
2 an adherent of an ideology.
Etymology:
F id{eacute}ologue f. Gk idea (see IDEA) + -LOGUE