The rivalry between Glasgow clubs Rangers and Celtic, popularly known the “Old Firm” is historically tied up in religion and subsequently politics. Sectarianism in Glasgow takes these forms, and the fierce rivalry between Celtic F.C. and Rangers F.C. only reinforces the same.
Celtic was founded by Catholic immigrants, while Rangers has always been perceived as the “Protestant club”. In fact, up until 1989, when Mo Johnston signed for them, Rangers had never fielded a high-profile Catholic player.
The two clubs share a long and passionate mutual enmity that transcends the sporting arena. Undoubtedly, this is one of the most heated rivalries in the world.