The road to faith passes through obedience to the call of Jesus. Unless a definite step is demanded, the call vanishes into thin air, and if men imagine that they can follow Jesus without taking this step, they are deluding themselves like fanatics.

…The following two propositions hold good and are equally true: only he who believes is obedient, and only he who is obedient believes.

from The Cost of Discipleship

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Gender-inclusive paraphrase:

The road to faith passes through obedience to the call of Jesus. Unless a definite step is demanded, the call vanishes into thin air, and if mortals imagine that they can follow Jesus without taking this step, they are deluding themselves like fanatics.

…The following two propositions hold good and are equally true: only those who believe are obedient, and only those who are obedient believe.

from The Cost of Discipleship