1. Spiritual disagreements

    Disunity between individual souls is so strong within this material world that even in a society of Krsna consciousness, members sometimes appear disunited due to their having different opinions and leaning toward material things. Actually, in Krsna consciousness there cannot be two opinions. There is only one goal: to serve Krsna to one's best ability. If there is some disagreement over service, such disagreement is to be taken as spiritual. Those who are actually engaged in the service of the Supreme Personality of Godhead cannot be disunited in any circumstance.

    From Srila Prabhupada's purport to SB 4.30.8