As with the unity of the church, the second creedal mark is a deeply theological statement. The church’s holiness stems not from its members but from its relationship to Christ and from the salvation that it enjoys through faith in him. This is made clear in passages such as Ephesians 1:3-14 and 5:25-27. Hans Küng expresses it thus:
It is God who distinguishes the church, sets it apart, marks it out for his own and makes it holy, by winning power over the hearts of men through his Holy Spirit, by establishing his reign, by justifying and sanctifying the sinner and thereby founding the communion of saints.
Holiness in this sense arises out of an encounter with the living God. While it is not primarily an ethical concept, holiness inevitably involves an ethical element. God not only calls men and women to himself through Christ. He also calls them to be holy and empowers them to live in holiness.
The holiness of the church speaks of the sanctification of each of its members and of the ongoing work of the Spirit of holiness in their lives. William Willimon writes of the church as a counter-cultural phenomenon, a colony of heaven.
In its very existence, the church serves the world not by running errands for the world but by providing a light for the world, that is, by providing an imaginative alternative for society. The chief political task for the church is not to provide suggestions on social policy but to be in our very existence a social policy.
Part of the church’s mandate is to encourage, model and teach a lifestyle among its members that truly lays hold of its identity as salt and light in the world. This mandate will be achieved not through an emphasis on externals, but as Christians are drawn into the costly love of Christ and begin to interpret it in terms of their own lives. Donald Bloesch writes,
What is here proposed is holiness in the world, a piety that is to be lived out in the midst of human suffering and dereliction… Holiness is a gift of God, but it is also a goal that we are called to strive for in this world, in this life. We are summoned neither to separation from nor to solidarity with the world but rather to combat with the evil forces of the world, and this means that the way of holiness is also the way of the cross.