The book of Titus teaches Cretan believers how to live godly lives in their sinful society. God's love and grace transforms their lives, and they can then share the gospel with the world.
Paul also reminded Cretan believers that while they lived in a sinful culture, they could be transformed into a new humanity by the same grace that Jesus demonstrated when He died to redeem them.
As new humanity, they could say no to a lifestyle that was inconsistent with God's generous love. They could also show God's salvation message and transform their communities by participating in Cretan culture, rejecting anything corrupt, embracing good, living and devoting themselves to Jesus and promoting the common good.