A Kṛṣṇa conscious being is always engaged in planning how to take all of suffering humanity back home, back to Godhead. Even if one is not successful in reclaiming all the fallen souls back to Godhead, still, because he is Kṛṣṇa conscious, his path to Vaikuṇṭhaloka is open. He personally becomes qualified to enter the Vaikuṇṭhalokas, and if anyone follows such a devotee, he also enters into Vaikuṇṭhaloka.
(Srimad Bhagavatam---4:12:36---purport).

The Lord makes so many promises for the benefit of suffering humanity. Although the Lord is very compassionate upon suffering humanity, human beings are generally not very anxious to serve Him. The relationship is something like that between the father and the son; the father is always anxious for the welfare of the son, even though the son forgets or neglects the father.
(Srimad Bhagavatam---4:22:42---purport).

When a person is advanced in spiritual consciousness or Kṛṣṇa consciousness, he naturally becomes very sympathetic toward all living entities suffering in the material world. Naturally such an advanced person thinks of the suffering of the people in general. However, if one does not know of the material sufferings of fallen souls and becomes sympathetic because of bodily comforts, as in the case of Bharata Mahārāja, such sympathy or compassion is the cause of one's downfall. If one is actually sympathetic to fallen, suffering humanity, he should try to elevate people from material consciousness to spiritual consciousness.
(Srimad Bhagavatam---5:8:9---purport).

Only a person who is fully in Kṛṣṇa consciousness can be said to be engaged in welfare work for all living entities. When a person is actually in the knowledge that Kṛṣṇa is the fountainhead of everything, then when he acts in that spirit he acts for everyone. The sufferings of humanity are due to forgetfulness of Kṛṣṇa as the supreme enjoyer, the supreme proprietor, and the supreme friend. Therefore, to act to revive this consciousness within the entire human society is the highest welfare work. One cannot be engaged in such first-class welfare work without being liberated in the Supreme. A Kṛṣṇa conscious person has no doubt about the supremacy of Kṛṣṇa. He has no doubt because he is completely freed from all sins. This is the state of divine love.
(Bhagavad-Gita---5:25---purport).

Nature is said to be the cause of all material causes and effects, whereas the living entity is the cause of the various sufferings and enjoyments in this world.
(Bhagavad-Gita---13:21---translation).

Constant transmigration of the soul from one body to another is the cause of suffering in material existence. This conditional life in material existence is called saṁsāra. One may perform good work and take his birth in a very nice material condition, but the process under which birth and death take place is like a terrible fire.
(Srimad Bhagavatam----3:21:17---purport).

The Supreme Lord knows everything about the suffering of the conditioned soul, and therefore He appears in this material world, sometimes personally, sometimes by an incarnation and sometimes by authorizing a living being to act on His behalf.
(Srimad Bhagavatam---8:24:46---purport).