SB 11.14.18
badhyamano ’pi mad-bhakto
visayair ajitendriyah
prayah pragalbhaya bhaktya
visayair nabhibhuyate
Translation:
My dear Uddhava, if My devotee has not fully conquered his senses, he may be harassed by material desires, but because of his unflinching devotion for Me, he will not be defeated by sense gratification.
Purport:
Abhibhuyate indicates falling down into the material world and being defeated by maya. But even though one’s senses are not fully conquered, one who has unflinching devotion for Lord Krsna does not run the risk of being separated from Him. The words pragalbhaya bhaktya indicate a person who has great devotion for Lord Krsna, and not one who desires to commit sinful activities and chant Hare Krsna to avoid the reaction. Because of previous bad habits and immaturity, even a sincere devotee may be harassed by lingering attraction to the bodily concept of life; but his unflinching devotion for Lord Krsna will act. Srila Visvanatha Cakravarti Thakura gives the following two examples. A great warrior may be struck by the weapon of his enemy, but because of his courage and strength he is not killed or defeated. He accepts the blow and goes on to victory. Similarly, one may contract a serious disease, but if he takes the proper medicine he is quickly cured.
If those who follow the impersonal system of speculation and austerity deviate even slightly from their path, they fall down. A devotee, however, even though immature, never falls from the path of devotional service. Even if he displays occasional weakness, he is still considered a devotee if his devotion to Lord Krsna is very strong. As the Lord states in Bhagavad-gita (9.30):
api cet su-duracaro
bhajate mam ananya-bhak
sadhur eva sa mantavyah
samyag vyavasito hi sah
“Even if one commits the most abominable actions, if he is engaged in devotional service he is to be considered saintly because he is properly situated.”