There is no question of believe. Don't bring this question-belief. It is law. Just like there is government, you believe or not believe, who cares for you? That is government. Similarly, you believe or not believe, there is God. If you don't believe in God and do independently whatever you like, then you'll be punishable.
-Radio Interview -- July 27, 1976, London

वासुदेवे भगवति भक्तियोग: प्रयोजित: ।
जनयत्याशु वैराग्यं ज्ञानं च यदहैतुकम् ॥ ७ ॥
By rendering devotional service unto the Personality of Godhead, Śrī Kṛṣṇa, one immediately acquires causeless knowledge and detachment from the world.
-SB 1.2.7