terms for God's people.

terms used for God's people in the NT...

Term (singular, plural)
Disciple – 290
Brother – 202
Saint – 45
Child of God – 30
Follower – 9
Holy people/nation – 4
Student – 3
Christian – 3
People of God – 3
Church - 110

my questions:
-what term would people most understand?
-what term, if any, is the one God would have us use?
-is there any significance to the fact some terms are used in the gospels/acts, and others are used in the letters?