neophyte

Short definition from Wiktionary

Noun

1. 1
   A beginner; a person who is new to a subject, skill, or belief.
2. 2
   A novice (recent convert); a new convert or proselyte; a new monk.
3. 3
   Among the early Christians, and still among the Roman Catholics, one who has recently embraced the Christian faith, and been admitted to baptism, especially those converts from heathenism or Judaism.
4. 4
   A plant species recently introduced to an area (in contrast to archaeophyte, a long-established introduced species).