When he (person born in a particularly righteous, aristocratic or sacred family) is finally free from all contaminations, he attains the supreme perfection-Krsna consciousness. BG 1972 purports

Expressions researched:
"When he is finally free from all contaminations, he attains the supreme perfection-Kṛṣṇa consciousness"

Bhagavad-gita As it is

BG Chapters 1 - 6

A person born in a particularly righteous, aristocratic or sacred family becomes conscious of his favorable condition for executing yoga practice. With determination, therefore, he begins his unfinished task, and thus he completely cleanses himself of all material contaminations. When he is finally free from all contaminations, he attains the supreme perfection-Kṛṣṇa consciousness.

BG 6.45 (1972), Translation and Purport

But when the yogī engages himself with sincere endeavor in making further progress, being washed of all contaminations, then ultimately, after many, many births of practice, he attains the supreme goal.

A person born in a particularly righteous, aristocratic or sacred family becomes conscious of his favorable condition for executing yoga practice. With determination, therefore, he begins his unfinished task, and thus he completely cleanses himself of all material contaminations. When he is finally free from all contaminations, he attains the supreme perfection-Kṛṣṇa consciousness. Kṛṣṇa consciousness is the perfect stage of being freed of all contaminations. This is confirmed in the Bhagavad-gītā:

yeṣāṁ tvanta-gataṁ pāpaṁ janānāṁ puṇya-karmaṇām

te dvandva-moha-nirmuktā bhajante māṁ dṛḍha-vratāḥ

"After many, many births of executing pious activities, when one is completely freed from all contaminations, and from all illusory dualities, one then becomes engaged in the transcendental loving service of the Lord."