From our house I can see the Church of St Mary at Newchurch in Pendle - it is my parish church, my husband is church surveyor and some discoveries have come about during recent extensive restoration work on the tower.
The Eye of God feature predates the position of the 1653 date stone. Externally if consists of 2 individual curved stone pieces coming together to form a lozenge shape and the ‘eye’ is a piece of blue slate surrounded by a sand and cement infill. ie. it’s not lime mortar. This puts the infill sometime later than 1850. It is topped with a rectangular drip stone. Internally (and I’ve been up the tower to have a look) the now infilled opening is roughly rectangular shaped and the shape is consistent with it having once been a window.
Therefore I think the bit that KGarrad quotes from
http://www.martintop.org.uk/blog/eye-god-newchurch-pendle makes sense:-
More likely, it was carved so bell-ringers or their assistants could see approaching wedding and funeral parties, and wasn’t originally filled in. This is, after all, one of the few churches in the country that affords no views whatever of the road that approaches it.
However
"If carvings could really keep witches away, every church in the country would have had one.
I recently attended a day course of medieval graffiti on stone and wood and it was fascinating. In more superstitious times stone and woodwork would be marked in a variety of ways in the belief that such marks would ward off evil spirits. Doorways, window frames, gate posts etc would be marked in a huge variety of ways and most are easily missed unless you are aware what you are looking for and churches provide a rich source. That is not to say that this explains the Eye of God at St Mary's though.
http://www.medieval-graffiti.co.uk/page7.htmlhttp://www.medieval-graffiti.co.uk/page5.html