Professor N.E. Pestov. "Modern practice of Orthodox virtue".
The beginning of delusion can be determined on the following grounds:
1) Self-confidence, following own will, unwillingness to subordinate own will to the elder or spiritual father and to the authority of the Church’s consciousness.
2) Self-direction – also called "self-centeredness" or "autoeroticism" – is egoism with lack of love, gentleness and forbearance to the surrounding people (except, perhaps, the closest family members).
3) Keeping the attention on certain statements (thoughts) of the spiritual sphere; the deluded people are mainly guided in life by these thoughts, ignoring the basic commandments of God and the teachings of the Church. These ideas can be taken from the Holy Scriptures, but they are isolated from the general spirit of the Holy Gospel. Then they divert the deluded person from the main virtues - love, humility, obedience and gentleness.
How to protect yourself from delusion:
1) It is obvious that the most radical remedy is to be in obedience to the elder or spiritual father, and if one can not have them – then to be guided by the views and advice of those Christians who succeeded in spiritual wisdom.
2) At the same time, each Christian must study the Scriptures and the works of the Holy Fathers of the Church.
3) Everybody should be keep from having opinions that do not agree with the general church consciousness.
4) We should always be sensitive to the views of friends and associates, be attentive to their judgments and carefully analyze our disagreements with them. We should remember that the Lord often rebukes us through the mouth of our loved ones.