Bhagavad-gītā As It Is · Text 4.40
Spiritual master, knowledge and removal of doubt
अज्ञश्चाश्रद्दधानश्च संशयात्मा विनश्यति ।
नायं लोकोऽस्ति न परो न सुखं संशयात्मनः ॥ ४० ॥
ajñaś cāśraddadhānaś ca
saṁśayātmā vinaśyati
nāyaṁ loko ’sti na paro
na sukhaṁ saṁśayātmanaḥ
But ignorant and faithless persons who doubt the revealed scriptures do not attain God consciousness; they fall down. For the doubting soul there is happiness neither in this world nor in the next.
Read Śrīla Prabhupāda's purport on Vedabase.io