The most high-minded protest sign seen during the Pope’s visit to the UK:
For those unfamiliar with filioque, here is a quick overview from Graham Cole:
Filioque: Lat., “and from the Son.” Refers to the procession of the Spirit within the triune Godhead. Added to the Niceno-Constantinopolitan Creed in the West without Eastern Church approval. According to Eastern theology, the Spirit proceeds from the Father alone. A key point of contention between creedal Western churches and Eastern ones, especially since the split of A.D. 1054.
HT: Scotteriology via Euangelizomai