Because the root of sinful desire is not destroyed in the heart of a person who is cultivating knowledge but who has no taste for devotional service, there is a possibility that his sinful desires will reappear

Expressions researched:
"because the root of sinful desire is not destroyed in the heart of a person who is cultivating knowledge but who has no taste for devotional service, there is a possibility that his sinful desires will reappear"

SB Canto 6

In the previous verse Śukadeva Gosvāmī gave the example that the dried leaves of creepers beneath a bamboo tree may be completely burnt to ashes by a fire, although the creepers may sprout again because the root is still in the ground. Similarly, because the root of sinful desire is not destroyed in the heart of a person who is cultivating knowledge but who has no taste for devotional service, there is a possibility that his sinful desires will reappear.

SB 6.1.15, Translation and Purport:

Only a rare person who has adopted complete, unalloyed devotional service to Kṛṣṇa can uproot the weeds of sinful actions with no possibility that they will revive. He can do this simply by discharging devotional service, just as the sun can immediately dissipate fog by its rays.

In the previous verse Śukadeva Gosvāmī gave the example that the dried leaves of creepers beneath a bamboo tree may be completely burnt to ashes by a fire, although the creepers may sprout again because the root is still in the ground. Similarly, because the root of sinful desire is not destroyed in the heart of a person who is cultivating knowledge but who has no taste for devotional service, there is a possibility that his sinful desires will reappear. As stated in Śrīmad-Bhāgavatam (10.14.4):

śreyaḥ-sṛtiṁ bhaktim udasya te vibho

kliśyanti ye kevala-bodha-labdhaye

Speculators who undergo great labor to gain a meticulous understanding of the material world by distinguishing between sinful and pious activities, but who are not situated in devotional service, are prone to material activities. They may fall down and become implicated in fruitive activities. If one becomes attached to devotional service, however, his desires for material enjoyment are automatically vanquished without separate endeavor. Bhaktiḥ pareśānubhavo viraktir anyatra ca: (SB 11.2.42) if one is advanced in Kṛṣṇa consciousness, material activities, both sinful and pious, automatically become distasteful to him. That is the test of Kṛṣṇa consciousness. Both pious and impious activities are actually due to ignorance because a living entity, as an eternal servant of Kṛṣṇa, has no need to act for his personal sense gratification. Therefore as soon as one is reclaimed to the platform of devotional service, he relinquishes his attachment for pious and impious activities and is interested only in what will satisfy Kṛṣṇa. This process of bhakti, devotional service to Kṛṣṇa (vāsudeva-parāyaṇa), relieves one from the reactions of all activities.