The question was why a sinful man commits sinful activities although he has full knowledge of the after result by knowing it from authority and by seeing it personally. A thief commits theft repeatedly and is imprisoned repeatedly, and he has full knowledge of it—then what is the cause of his putting himself into miserable condition of prison life?
The cause is diagnosed by Vedic Acaryas as the papa bija or the seed of sinful activities. This papa bija remains dormant within our heart in three stages—dormant, seedling and fructified. This chain of different stages of our papa bija is the cause of repeated birth and death transmigration in different species of life.
Actually this is the cause of suffering of the living entities. There are many processes for delivering the living entity from this life of entanglement. Generally it is summarized in the process of meditation, performances of great sacrifices and worshiping the Lord in the temple. But in this Age of Kali Yuga nobody can meditate perfectly, neither they have sufficient resources for performing great sacrifices, neither they have tendency to attend spiritual services in the temple, churches, or mosques or any such sanctuaries. Therefore, in the Brhad Naradiya Puranam it is stated that none of these three principles of spiritual upliftment is possible to perform in this Age of Kali. Therefore, the only possible means of spiritual realization is chanting the Holy Name of God or Krishna or Rama. Lord Caitanya propagated this formula of spiritual realization 500 years ago; and by His grace now it is introduced in the Western world, and practically we are experiencing that it is effective.