Cannot Fail? Really?

...the Third Step corresponds to the principle of faith. Once we truly make the leap to believe, no matter what, that a power greater than ourselves will restore us to sanity and will take care of every other issue in our lives as well, we cannot ever fail to recover, and the compulsion to binge disappears. ~ Overeaters Anonymous. Voices of Recovery . Overeaters Anonymous. Kindle Edition. Step Three: "Made a decision to turn our will and our lives over to the care of God as we understood Him." How do we know exactly when we have actually made a decision to believe, no matter what, that a power greater than ourselves will restore us to sanity? Is it once and for all times? Or is there wiggle room? Are we entitled to sometimes run hot, fully convinced, and sometimes be riddled with doubt? I find encouragement in the Twelve Steps and TwelveTraditions'assertion, "“Once we compulsive overeaters truly take the Third Step we cannot fail to recover.” So somewhere there's inevitability assured, but as long as I find wiggle room, I can usually find it!