Any amount of mental speculation on the strength of material science and knowledge without any bona fide touch with the Absolute Truth is sure to be a mundane untruth and failure, simply due to not being in touch with the Absolute Truth. Such godless, unfaithful words and actions, however materially enriched, are never to be trusted. . . . A grain of devotion is more valuable than tons of faithlessness.- His Divine Grace A. C. Bhaktivedanta Swami Prabhupada Srimad-Bhagavatam 2.6.34, Purport

The Supreme Lord is situated in everyone’s heart, O Arjuna, and is directing the wanderings of all living entities, who are seated as on a machine, made of the material energy. O scion of Bharata, surrender unto Him utterly. By His grace you will attain transcendental peace and the supreme and eternal abode.- Lord Sri Krishna Bhagavad-gita, 18.61–62

All the bodies of the Supreme Soul are eternal and unchanging. They never undergo loss or gain, and they are never creations of material nature. In all conditions they are full of the greatest intense bliss and pure consciousness, endowed with all auspicious qualities, and devoid of all faults. The bodies of the Supreme are free from defects, unsurpassed in excellence, and full in all transcendental qualities. Thus the supreme controller’s body and soul are never different from one another. – Maha-varaha Purana (Quoted in Brhad-bhagavatamrta 2.2.160)

When one thinks of Krishna constantly, love for Him manifests within the heart. Even though one may be ignorant, one can reach the far shore of the ocean of transcendental love by Lord Krishna’s mercy.- Sri Caitanya Mahaprabhu Sri Caitanya-caritamrta, Madhya-lila 19.236

A devotee should always try to hear about spiritual matters and should always utilize his time in chanting the holy name of the Lord. His behavior should always be straight forward and simple, and although he is not envious but friendly to everyone, he should avoid the company of persons who are not spiritually advanced.- Lord Kapila Srimad-Bhagavatam 3.29.18

Even though one may have gone to the other side of all the Vedas, and even though one is well versed in all the revealed scriptures, if one is not a devotee of the Supreme Lord, he must be considered the lowest of mankind.- Garuda Purana (Quote in Srimad-Bhagavatam 2.9.36, Purport)