The conditioned life of a living being is caused by his revolting against the Lord. There are men called deva, or godly living beings, and there are men called asuras, or demons, who are against the authority of the Supreme Lord. In the Bhagavad-gītā (BG Sixteenth Chapter) a vivid description of the asuras is given in which it is said that the asuras are put into lower and lower states of ignorance life after life and so sink to the lower animal forms and have no information of the Absolute Truth, the Personality of Godhead.
-Shrimad Bhagvatam Canto 1 Chapter 2 Verse 16, Translation and Purport

यो मामजमनादिं च वेत्ति लोकमहेश्वरम् ।
असम्मूढ: स मर्त्येषु सर्वपापै: प्रमुच्यते ॥ ३ ॥
He who knows Me as the unborn, as the beginningless, as the Supreme Lord of all the worlds – he only, undeluded among men, is freed from all sins.
-Bhagavad-Gita Chapter 11 Verse 3