Christians need to hear the gospel as much as non-Christians. Why?
1/ Because there are plenty of people who identify as Christians who aren’t living by faith; who are Christian in name only. They need to hear the gospel.
2/ Because there are plenty of Christians whose faith is immature; who haven’t integrated the gospel into the their life and teaching even after many years in church (or even ministry); who need deeper roots so they can produce healthier fruit. They need to hear the gospel.
3/ Because growing in grace is essential for growing in Christ even for mature Christians. Grace is not just the ABCs of Christianity, it is A-Z. Everyone needs to hear the gospel.