Alongside Orthodox Christianity (see our churches guide), a layer of older folk belief and superstition persists across Greece, Santorini included — most visibly in one specific, very common object.
The mati (evil eye)
The blue glass eye charm — sold everywhere from souvenir shops to jewellery boutiques — represents protection against the "evil eye" (mati), a folk belief that envy or ill-wishing, even unintentional, can bring bad luck or harm to the person it's directed at. Wearing or displaying a mati charm is a widespread, casual practice rather than a deeply religious one; you'll see it on jewellery, hung in cars, and above shop doorways as commonly as any explicitly religious symbol.
Xematiasma
A traditional practice of "removing" the evil eye through a specific set of prayers, sometimes combined with oil and water, still exists among some older or more traditional families, generally performed by a woman who has learned the specific ritual. It's not something you're likely to directly encounter as a visitor, but it's a real, still-practised tradition rather than a purely historical one.
Name days
Greeks traditionally celebrate their name day (the feast day of the saint they're named after) with more significance than their birthday — worth knowing if a local mentions celebrating one, since it's a genuine, ongoing social occasion rather than an obscure custom.
Why this matters as a visitor
None of this requires any particular behaviour from you — but recognising the mati for what it is (a real folk-protective symbol, not just a pretty souvenir pattern) adds context to something you'll otherwise see everywhere on the island without understanding it.
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