"There are pious men and sinful men. Sinful men cannot become devotee. Pious men can become devotee.
yesam tv anta-gatam papam
bhajante mam drdha-vratah
These are the definitions. One who is completely free from all sinful activities, they can become pure devotee. So even after becoming free from sinful activities, if one has got some motive, then he is also not pure devotee. Pure devotee means without any material motive: 'God is great. I am His subordinate. I must love God. I must render service to God.' This is
pure devotee. And if I go to God, 'Please give me my bread,' that is not pure devotee, because he has got some purpose. As soon as his purpose is fulfilled, he may turn nondevotee. Just like one of my German Godbrothers said that in Germany during the last war, Second World War, many women used to go to the church to pray to God to get back their husband, son, or brother. But nobody came back. And they became atheist: 'There is no God. We prayed so much, and my father did not come, my brother did not come, my son
did not come.' So motivated devotion is sometimes frustrated, and they become atheist. Therefore the devotee who has no motive is pure devotee. 'In any condition, it is my duty to love God and to serve Him, not for my benefit but God's satisfaction.' That is pure devotee."
(Srila Prabhupada Room Conversation, March 1, 1975)