(Lord Nrsimhadeva slaying Hiranyakasipu and his army of demons)
Devotee: This material world, there are demons, and then there are saintly persons. This is the nature of the material world. And Kṛṣṇa comes. The demons want to forget Kṛṣṇa, and that's their job.
Prabhupāda: Demons means who harass saintly persons. That is the definition of demon. Demons means one who harasses saintly persons and who does not believe in God. This is the definition of demon. So there is a class of men always who do not like saintly persons and do not believe in God. So they are demons.
Dvau bhūta-sargau loke daiva āsura (BG 16.6). There are two kinds of men: daiva, asura; demon and demigod. Viṣṇu-bhakto bhaved daiva asuras tad-viparyayaḥ. Those who are devotees of the Lord, they are called demigods, and those who are opposite number, they are called demons. The whole world is full of demons; still there are little percent of them are devotees. Otherwise the material world is full of demons.
Devotee (2): (in background) All glories to Śrīla Prabhupāda. All glories to saṅkīrtana. Come join the saṅkīrtana party.
Devotee (3): The demons' business is to harass the devotees? They do nothing else?
Devotee (3): The demons, they do nothing else except harass the devotees?
Prabhupāda: Demons means who harasses devotee. That is demon. Anyone who harasses devotee, he is demon.
(Srila Prabhupada Lecture, Los Angeles, June 25, 1972)