Because of so-called improvements in material opulence, people have entirely given up the path of realization. Practically no one is interested in God, one's relationship with God, or how one should act. Modern men have altogether forgotten such questions because they are mad for material possessions. If this kind of civilization continues, the time will soon come when the Supreme Personality of Godhead will take away all the material opulences. Then people will come to their senses.

His Divine Grace A.C. Bhaktivedanta Swami Prabhupada
Srimad-Bhagavatam, 8.22.17, Purport

The Supreme Person, Sri Krsna Himself, who is the life of Srimati Radharani and is the Lord of the universe in creation, maintenance, and annihilation, appears as Gaura [Lord Caitanya Mahaprabhu], O Mahesvari.

Lord Ananta Sesa
Ananta Samhita

After searching through all the Vedic literature, one cannot find a method of religion more sublime for this age than the chanting of Hare Krsna.

Kali-santarana Upanisad

There is no eye equal to knowledge, no austerity equal to speaking the truth, no misery equal to attachment, and no happiness equal to detachment.

Canakya Pandita

If one is worshiping Lord Hari [Krsna], what is the use of performing extraneous penances? And if one is not worshiping Lord Hari, no such penances will save one.

Narada Muni
Narada Pancaratra

Just as those who are greedy see everything as a source of money-making and those who are lusty see everything as conducive to sex, the most perfect devotee sees Narayana [Krsna] everywhere.

Source unknown
Quoted in Srimad-Bhagavatam 7.7.55, Purport

The neophyte Vaisnava devotees' ringing the bell even once during worship of the Deity of the Supreme Lord is a million times more valuable, spiritually and otherwise, than the charitable fruitive workers' building hospitals, feeding thousands of the poor, or building homes, or even the empiric philosophers' Vedic studies, meditation, austerities, and penances.

Srila Bhaktisiddhanta Sarasvati Thakura