This paper presents the opportunities of GIS analysis supported by Spearman’s correlation method for answering the question whether in the western, Latin part of the Roman Empire there are spatial continuations between the ancient Roman waterbody-connected cults of Isis and Neptune on one hand and the late antique Christian cult of saint Mary on the other.

In the last years there is a trend of studies using geographical analysis for investigating connections of various ancient phenomena including the cults of Graeco-Roman gods. Hovewer, spatial proximity between two phenomena measured as distances in kilometers alone is not sufficient evidence of their connection until we compare this proximity with other selected as well as random phenomena and test it statistically.

There is an older scholarly tradition suggesting a connection between the Graeco-Roman cult of Isis and the late antique Christian cult of holy Mary, Mother of Christ, often emphasizing shared maternal characteristics. The correlation between the two cults in certain areas associated with seafaring may seem somewhat surprising. One may ask whether the late antique cult of Mary did not respond to the old needs of seafarers.