The Bhagavad-gita primarily deals with the intelligence of man, leading one to the progressive path of civilization of the spirit soul. And Srimad-Bhagavatam is the complete human civilization dealing with the subject matter of the soul proper. As soon as a man is raised to the status of the civilization of the soul, he is fit to be promoted to the kingdom of God.
His Divine Grace A. C. Bhaktivedanta Swami Prabhupada
Srimad-Bhagavatam 2.7.18, Purport

What power does the name of Krishna possess? My heart constantly burns in the fire of worldly desires, just like a desert scorched by the rays of the sun. The holy name, entering the core of my heart through the holes of my ears, showers unparalleled nectar upon my soul.
Srila Bhaktivinoda Thakura
Sri Nama-mahatmya 1, from Saranagati

O brothers, please hear My truthful statement. Worship the invaluable wealth of Krishna’s lotus feet. O brothers, may you all desire to attain the same lotus feet that Lakshmi desires to serve, the same lotus feet by whose worship Lord Shiva has became known as a pure servant, and the same lotus feet from which the Ganges emanated.
Sri Chaitanya Mahaprabhu
Sri Chaitanya-bhagavata, Madhya-khanda 1.165–167

What is the direction of all Vedic literatures? On whom do they set focus? Who is the purpose of all speculation? Outside of Me no one knows these things. Now you should know that all these activities are aimed at ordaining and setting forth Me. The purpose of Vedic literature is to know Me by different speculations, either by indirect understanding or by dictionary understanding. Everyone is speculating about Me.
Lord Sri Krishna
Srimad-Bhagavatam (11.21.42–43)

An intelligent person does not take interest in a place, even in the topmost planetary system, if the pure Ganges of topics concerning the Supreme Lord’s activities does not flow there, if there are no devotees engaged in service on the banks of such a river of piety, or if there are no festivals of sankirtana-yajna to satisfy the Lord [especially since sankirtana-yajna is recommended in this age].
Demigods
Srimad-Bhagavatam 5.19.24

The self-effulgent Vaikuntha planets, by whose illumination alone all the illuminating planets within this material world give off reflected light, cannot be reached by those who are not merciful to other living entities. Only persons who constantly engage in welfare activities for other living entities can reach the Vaikuntha planets.
Maitreya Rishi
Srimad-Bhagavatam 4.12.36

O Vishnu! Your name is spiritual in nature and self-effulgent. Thus even though we understand but a fraction of its glories, by merely repeating its syllables we attain a refined intelligence capable of understanding the Lord.
Rig-veda 1.156.3
Quoted in Baladeva Vidyabhushana’s commentary on Rupa Goswami’s Namashtaka 3