Jeremiah 17:9
Jeremiah 17:99The heart is deceitful above all things and beyond cure. Who can understand it?
When the verse appears in JW teaching, it is usually applied to the outsider — the worldly person whose heart misleads them, the apostate whose corrupt heart leads them away from the truth. The Watchtower rarely turns the verse on the JW themselves to ask whether their trust in the Governing Body's interpretation could itself be a heart-deception.
The verse is the classical Reformation proof-text for the noetic effects of the fall — that the heart is so unreliable that subjective certainty cannot adjudicate between competing religious claims. A Mormon, a Muslim, a Witness, and a Reformed Christian all feel sincerely certain. If the heart is deceitful, sincerity alone cannot rescue any of them. The differentiator must be external and objective: Scripture, tested honestly against itself ( — "your word is truth"). That clears the ground for every doctrinal conversation: "if our hearts can mislead us, what is the standard by which we tell?"
Where most English translations follow the King James and Geneva tradition — "deceitful above all things, and desperately wicked" — the NWT renders the same Hebrew as "more treacherous than anything else and is desperate." The substitution of "treacherous" for "deceitful" is defensible, but "is desperate" replaces what the Hebrew anush conveys — incurably sick, terminally corrupt, beyond repair. The doctrinal effect is to soften a verse that confronts every reader with the unfixable depth of their own heart's corruption. Pair this with the JW two-tier anthropology — full indwelling reserved for the 144,000 — and the softening makes pastoral sense for the system, but flattens what the prophet actually wrote.