Bhagavad Gita Chapter 4, Verse 40

अज्ञश्चाश्रद्धानश्च संशयात्मा विनश्यति | नायं लोकोऽस्ति न परो न सुखं संशयात्मनः ||

ajñaś cāśraddhānaś ca saṁśayātmā vinaśyati nāyaṁ loko 'sti na paro na sukhaṁ saṁśayātmanaḥ

The ignorant, the faithless, and the doubting self perish. For the doubting self, there is neither this world nor the next, nor happiness.

Krishna warns against doubt: 'saṁśayātmā vinaśyati' (the doubting self perishes). Doubt destroys—it prevents knowledge, prevents faith, prevents progress. The three qualities that destroy—ignorance (not knowing), lack of faith (not trusting), and doubt (uncertainty)—keep you stuck. The phrase 'nāyaṁ loko 'sti na paro na sukhaṁ saṁśayātmanaḥ' (for the doubting self, there is neither this world nor the next, nor happiness) shows that doubt destroys everything—you can't enjoy this world (stuck in uncertainty), you can't reach higher goals (doubt prevents progress), you can't find happiness (doubt creates suffering). This verse emphasizes the destructive power of doubt—it's not neutral, but actively harmful. The antidote is faith, knowledge, and commitment—opposites of ignorance, lack of faith, and doubt.