Okie:

I hope I didn't seem sniffy in my earlier comment; I'm just trying to be as precise as I can because this area of discussion can so easily get heated!  I read Dr. Murray's books at an early and impressionable age, and believed every word until I learned more about the subject.  Incidentally, Anne Ross (The Folklore of the Scottish Highlands,1976) has this to say about Shony:

This strange custom persisted down into the present century.  In Lewis, for example, the god was called Shony, a corruption no doubt for some ancient pagan divine name.  A man would wade up to his waist in the sea and pour ale into it at midnight on the Eve of Maundy Thursday; various chants are known, and one recorded by Carmichael is as follows:

O God of the sea,
Put weed in the drawing wave
To enrich the ground,
To shower on us food.

Everyone behind the man performing this ritual took up the chant; often the ceremony would be followed by food and drink and merry-making.  The patently pagan custom was seriously frowned on by the Protestant Church, but persisted nevertheless.

Obviously Dr. Ross' comments should be taken as a folklorist's gloss; as we both seem to agree, the participants in the custom would have seen no inconsistency between it and their more conventional Christian beliefs.

Malcolm