Ideologist

[,aɪdɪ'ɒlədʒɪst] or [,aɪdɪ'ɑlədʒɪst]

(noun.) an advocate of some ideology.

Checker: Tina--From WordNet

(n.) One who treats of ideas; one who theorizes or idealizes; one versed in the science of ideas, or who advocates the doctrines of ideology.

Checker: Rene