Materialists are always careful for maintaining his material status quo first, and then please Visnu. Although they profess to be devotees of Visnu.
Therefore the Krishna Consciousness persons are greater than such materialistic worshippers. Materialist person perform all pious activities or devotional activities for some material gain, and as soon as there is any hindrance in the path of material gain, they at once become demon.
Therefore bhakti means without any material desires. That is the sign of pure devotee.
- Letter to Satsvarupa written from Montreal, July 3 1968