Karl Barth: “the Christian life is a spiritual one”
In modern usage the term “spiritual” has wrongly been put in embarrassing proximity to the word “religious.” It should be related to this word only indirectly and not very firmly. What has been forgotten is that, among Christians at least, the word “spiritual” can denote only a new definition of the human spirit, of the whole of this spirit, by the Holy Spirit, so that it cannot refer to a variation or modification of human spiritual activity as such… Christians can be, but do not have to be, particularly religious people. Similarly, particularly religious people can become and be Christians, but if they do they are not Christians in their quality as specially religious people. They are fortunate if their being such does not prevent them from becoming and being Christians! Invocation of God the Father by his children, the spiritual Christian life, commences and continues as a human life within the whole life of the spirit and religion, to which it is always referred and with which it is always linked. Nevertheless, it will always represent and be a new thing. Religiosity does not need to call upon a fatherly God. Hence it does not need any special movement and act of God. It does not need any baptism, sending, outpouring, and gift of the Spirit. It may work itself out in this way and take this form. But the spiritual life lives in invocation of God the Father and would be null and void without this special movement and act of this God, without the work of the Holy Spirit.