grace: See study note on 1:2.
I became a servant: Paul describes himself as a servant of:
the gospel (see also Colossians 1:23),
of God (1 Corinthians 3:5; 2 Corinthians 6:4),
of Christ (2 Corinthians 11:23),
of the church (Colossians 1:25), and
of the new covenant (2 Corinthians 3:6).