There's a good bit of confusion over St. John. The church calendar has two St. John's feast days: St. John the Baptist on June 24, near the summer solstice, and St. John the Evangelist on Dec. 27, near the winter solstice.

The June one is formally known as "The Nativity of St. John the Baptist". Its June date comes from its being linked to the date of Jesus' birth. From St. Luke, Chapt. 1, we learn that Elisabeth (the cousin of Mary of Nazareth) became pregnant in her old age by her husband Zacharias; her child was named John, later known as John the Baptist. When she was 6 months pregnant, an angel appeared to Mary in Nazareth and announced that she would become pregnant by the Holy Spirit, which happened then and there after she expressed her consent. The Bible says nothing about when either of these events, or the birth of Jesus, took place, nor is there even a hint as to what season it might have been. At some point the date for the celebration of the birth of Jesus was settled on Dec. 25 (on grounds that have been debated ever since). So from that, the date for the Annunciation was fixed for March 25 (9 mos. earlier) and the date for the birth of John the Baptist become June 24 (3 mos. after the Annunciation).

There are other problems with the Biblical Johns. There are:
1. The author of the Gospel of John, called St. John the Evangelist (evangelist meaning bearer of good news, gospel meaning good news)
2. The author of the 1st, 2nd and 3rd Epistles of John, generally (but not universally) considered to be St. John the Evangelist
3. The author of the last book of the New Testament, the Revelation of John (Revelations), generally now considered not to be the same author, and frequently called St. John the Divine to distinguish him from the Evangelist. (the huge Episcopal cathedral in New York City is the Cathedral Church of St. John the Divine)
4. St. John the Baptist. No confusing him with anyone else.
5. The disciple of Jesus named John and referred to in St. John's Gospel as "the disciple whom Jesus loved". That Gospel says that the author was that disciple, but there is considerable doubt about this, since it is generally accepted that the Gospel of John was probably the last-written of the four Gospels and probably not until about 100 AD, or about 70 years after the events which the Gospel recounts.