"So the Great Commission is a program for cultural change. As individuals bow the knee to Christ, they discover that worshiping Jesus must lead to action, bringing Jesus' teachings to bear on everything. So the kingdom brings individuals to Christ and also brings those individuals to exalt him in every area of life. It is both individual and social change, until God consummates the kingdom at the return of Jesus to judge the living and the dead." - Frame, ST, p93.
We must repent of our individualistic assumptions. As an individual is sanctified, that sanctification never remains solely "in" him. He is changed and so the world around him will be affected. And as the world around him is affected, the culture is changed. The yeast spreads, the tree grows, the waters cover the sea.