The conspiracy theories I have heard:

- Gargamel is a priest, the smurfs are prosecuted by the church

- Papa smurf wears red and has a beard because of ideological reasons, the smurfs political and economic system resembles communism

- Smurfs represent the seven deadly sins/seven capital vices

    Lust: Enamored smurf
    Gluttony: Baker smurf
    Avarice: Greedy smurf
    Sloth: Lazy smurf
    Wrath: Grouchy smurf
    Envy: Brainy smurf
    Pride: Vanity smurf

SMURF - Socialist Men Under Red Father