God is faithful (pisto o qeo). This is the ground of Paul's confidence as he loves to say ( 1 Thessalonians 5:24 ; 1 Corinthians 10:13 ; Romans 8:36 ; Philippians 1:16 ). God will do what he has promised. Through whom (di ou). God is the agent (di) of their call as in Romans 11:36 and also the ground or reason for their call (di on) in Hebrews 2:10 . Into the fellowship (ei koinwnian). Old word from koinwno, partner for partnership, participation as here and 2 Corinthians 13:13 ; Philippians 2:1 ; Philippians 3:10 . Then it means fellowship or intimacy as in Acts 2:42 ; Galatians 2:9 ; 2 Corinthians 6:14 ; 1 John 1:3 1 John 1:7 . And particularly as shown by contribution as in 2 Corinthians 8:4 ; 2 Corinthians 9:13 ; Philippians 1:5 . It is high fellowship with Christ both here and hereafter.