He remains faithful: This could mean that:
he gives those who have sinned a chance to ask God for forgiveness;
he judges non-Christians in truth according to his will that never changes;
he acts as a true example for his people to follow; and/or
he will achieve his purposes in history. He will save those who trust in him through the good news about Jesus (1:12; 2:19). See also Romans 3:3–4; 1 Corinthians 10:13; 1 John 1:9.