The history of Krishna the person has been openly seen by everyone, yet only those who are in love with the Supreme Personality of Godhead can appreciate this history, whereas nondevotees, who have not developed their loving qualities, think that the activities, form and attributes of the Supreme Personality of Godhead are fictitious.
In this connection, Srila Vishvanatha Chakravarti Thakura has given the example that persons suffering from jaundice cannot taste the sweetness of sugar candy, although everyone knows that sugar candy is sweet.
Similarly, because of the material disease, nondevotees cannot understand the transcendental name, form, attributes and activities of the Supreme Personality of Godhead, although they actually see the Lord's activities, either through authority or through history.
The Puranas are old, authentic histories, but nondevotees cannot understand them, especially Srimad-Bhagavatam, which is the essence of Vedic knowledge. Nondevotees cannot understand even the preliminary study of transcendental knowledge, Bhagavad-gita. They simply speculate and present commentaries with absurd distortions.
In conclusion, unless one elevates himself to the transcendental platform by practicing bhakti-yoga, one cannot understand the Supreme Personality of Godhead or His name, form, attributes or activities.
————Reference: Srimad Bhagavatam, Canto 10, Chapter 2, Purport of Text 36