Rav A. J. Heschel in Man is Not Alone:

To have no faith is callousness, to have undiscerning faith is superstition. “The simple believeth every word” (Proverbs 14:15), frittering away his faith on things explorable but not yet explored. By confounding ignorance with faith he is inclined to regard as exalted whatever he fails to understand, as if faith began where understanding ended; as if it were a supreme virtue to be convined without proofs, to be ready to believe.
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Those who are sure of their faith often tumble under their own weight, and, when overthrown, they fall on their knees, worshipping, deifying the snake that usually lies where flowers grow.
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It is tragically true that we are often wrong about God, believing in that which is not God, in a counterfeit ideal, in a dream, in a cosmic force, in our own father, in our own selves. We must never cease to question our own faith and to ask what God means to us. Is He an alibi for ignorance? The white flag of surrender to the unknown? Is He a pretext for comfort and unwarranted cheer? a device to cheat despondency, fear or despair?

From whom should we seek support for our faith if even religion can be fraud, if by self-sacrifice we may hallow murder? From our minds which have so often betrayed us? From our conscience which easily fumbles and fails? From the heart? From our good intentions? “He that trusteth in his own heart is a fool” (Proverbs 28:26).
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Individual faith is not self-sufficient: it must be counter-signed by the dictate of unforgettable guidance.

Significantly, the Shema, the main confession of Jewish faith, is not written in the first person and does not express a personal attitude: I believe. All it does is to recall the Voice that said: “Hear, O Israel.”

Not the individual man, nor a single generation by its own power, can erect the bridge that leads to God. Faith is the achievement of ages, an effort accumulated over centuries… There is a collective memory of God in the human spirit, and it is this memory of which we partake in our faith.