The name of a person has always carried great significance in the Bible. The changing of a person’s name is equally significant. The name reveals an aspect of the person’s character, or indicates a transformation that has taken place within them.
We honor the Saints because they lived their lives in an exceptionally holy manner. They put off sin; they acquired the Holy Spirit, became sanctified, and holy. As such, they are role models of how we should live while in this world. We aspire to be like them and seek their intercessions. Thus, we dedicate churches to their memory.
While our parish is dedicated to the Beloved Disciple, the church belongs to the Great God and Savior, our Lord Jesus Christ. He's the head of the Church, of which we are members. From a theological point of view, this is why we don't refer to the name of a parish by using a possessive, i.e., St. John’s.