glossary for new Christians

Sometimes I feel like I read the Bible like I’m learning to drive a manual car: lots of abrupt stopping and starting punctuated by bursts of exasperation.
There are so many words that I don’t understand and even more I don’t know how to pronounce. I started scrawling definitions in my bujo, but I wanted to share them with you.
I’m keeping it super simple: it’ll just be a list of words in alpha order, and I’ll be adding a few each week. Et voilà! A glossary for New Christians.
PS If you’re interested in a comprehensive glossary, I use the Evangelical Dictionary of Theology, second edition. As a new Christian, it almost needs a glossary for itself (!), but it’s super useful.
Apostle
A follower of Jesus, commissioned as a messenger.
Twelve selected people, as appointed by Jesus (Mark 3:14-19). They were:
Simon (to whom he gave the name Peter)
James, son of Zebedee
John, James' brother (to them he gave the name Boanerges, which means “sons of thunder”)
Andrew
Philip
Bartholomew
Matthew
Thomas
James, son of Alphaeus
Thaddaeus
Simon the Zealot
Judas Iscariot
Centurion
A soldier.
Covenant
A contract between God and His people.
Disciple
A dedicated follower and pupil of Jesus Christ. Every Christian is a disciple.
Further reading: Desiring God: What is a disciple?
The apostles are sometimes referred to as disciples, but disciples are not apostles. (See Apostles.)
Gospel
A Greek word meaning 'Good News', the Gospel is the message about Jesus' life, death and resurrection and what it means for us and the world.
A genre of bible writing. Matthew, Mark, Luke and John (the first four books of the New Testament) are gospels. These gospels are about Jesus' life, death, resurrection and teaching, written by people who were eyewitnesses.
Messiah
The King of Kings. There is only one Messiah: Jesus.
Preach
To deliver the word of God from the Bible.
Further reading: Desiring God: What I mean by preaching
Prophet
A person used as God's mouthpiece to deliver His message. Moses, Isaiah and Jesus himself were prophets.
Sin
A thought, word, action or inaction that goes against God's will.
We are all sinners. The only one who never sinned was Jesus.
Further reading: I am not a good person