Devotee: Srila Prabhupada, is it possible for one person to be part demon and part devotee in the same person?

Prabhupada: If he's a devotee, he's not demon at all, if he's devotee.

Devotee: But he may have some demoniac qualities?

Prabhupada: Yes. That, if he is seriously devotee, that demonic qualities will disappear very soon. Ksipram bhavati dharmatma. Api cet su-duracaro bhajate mam ananya-bhak sadhur eva sa mantavyah [Bg. 9.30]. Ksipram bhavati dharmatma. Just like electric fan is moving, and you make the switch off. Still you will find it is moving. But that movement will stop very soon, because switch is off. Similarly, a devotee, if it is sometimes found that he is demonic, that demonic, if he is sincerely a devotee, that demonic qualities will go very soon.

ksipram bhavati dharmatma
sasvac-chantim nigacchati
kaunteya pratijanihi
na me bhaktah pranasyati
[Bg. 9.31]

So if one is strongly a devotee, then, gradually — it may take little time — all good qualities will be manifest in his body.

From Srila Prabhupada's lecture on Bhagavad-gita 16.6 — October 18, 1975, Johannesburg