Definition: "100th" refers to a milestone or period in history, so "p100" refers to the first 100 years of Jesus Christ's life and teachings. The term was used by the early church for special occasions like baptism, but it comes from Old Testament times when God spoke with Adam (Genesis 2:5) and Eve (Genesis 3:17-19). It has been a metaphor ever since to signify something significant or vital at that time in history.