John displays a disappointing intolerance. He was probably still a very young man when this incident occurred. He would have been motivated by the relationship which he and the other disciples enjoyed with Jesus. While perfectly good in itself, it is easy to see how that relationship could, in a spiritually immature person, give rise to undesirable emotions: lack of a full awareness of the mission and person of Jesus leading to jealousy, and jealousy leading to intolerance.

Psalm 119:165 is almost a commentary on John's attitude: "Those who love your law have great peace, and for them there is no stumbling block". John undoubtedly loved Jesus, but obviously his love as yet lacked a certain depth and maturity. Immature love can often degenerate into possessiveness, as it appears to have done in John. Hence, the fact that someone outside their circle was using Jesus' name to expel demons became a stumbling block for him. Love that is fully mature will generate a great freedom, and so will bring great peace. The Psalmist found this peace and freedom in the Law of God. We shall find it in the Word of God made flesh, Jesus Christ.