I must say that the supposed meaning of the word irmin combined with the supposed function of Irminsul makes it very unlikely that irmin was the name of a god. If irmin means whole and Irminsul was seen as uniting heaven and earth (pillar of the whole, I would suggest then) it is by far more plausible that a pantheistic idea was expressed, such as can be found amongst the Stoics, the Indians and even among some Roman commentators on religion.