The whole "Masonic" business is an outgrowth of the Protestant Reformation, which endowed us with all kinds of critical thinking skills that kinda slid downhill into paranoia after a generation or two. Anything in a church that looked "weird" suddenly was labeled "Masonic" or "occult" or "papist" or "cabalist" or otherwise conspiracy-theoretical por los siglos de los siglos... This "eye in the sky" dates right back to Egypt, it is the symbol of God´s all-seeing presence. It is a popular image for church domes and the peaks of retablos, when an actual God the Father image won´t fit in the space, or was unfashionable. The Greeks used this, the Romans used it, the Visogoths did too. It shows up again, as in this example, in a neoclassical setting -- 16th or 17th century Enlightenment people harking back to Greece and Rome. It is, fundamentally, God watching Us. Over and over.
Unless you prefer the conspiracy theories, which will tell you all kinds of wild stuff that is "absolutely true."