For faith is only real when there is obedience, never without, and faith only becomes faith in the act of obedience.

Since, then, we cannot adequately speak of obedience as the consequence of faith, and since we must never forget the indissoluble unity of the two, we must place the one proposition that only he who believes is obedient alongside the other, that only he who is obedient believes. In the one case is the condition of obedience, and in the other obedience the condition of faith.

In exactly the same way in which obedience is called the consequence of faith, it must also be called the presupposition of faith.

from The Cost of Discipleship

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Gender-inclusive paraphrase version:

For faith is only real when there is obedience, never without, and faith only becomes faith in the act of obedience.

Since, then, we cannot adequately speak of obedience as the consequence of faith, and since we must never forget the indissoluble unity of the two, we must place the one proposition that only those who believe are obedient alongside the other, that only those who are obedient believe. In the one case is the condition of obedience, and in the other obedience the condition of faith.

In exactly the same way in which obedience is called the consequence of faith, it must also be called the presupposition of faith.

from The Cost of Discipleship