Prior to Christian times, the Triquetra (three interlocking circles) symbolized a three in one notion like mind, body, and spirit. However, when Christianity was introduced to Ireland the three in one concept came to be associated with the three aspects of God (the Father, the Son, and the Holy Spirit). The name of this three in one pattern also shifted to being called the Trinity. Of course, non-Christians still view it as a Triquetra with its associated meanings.

trinity, triquetra