But what are satanic promptings which afflict mankind?
They are the influx of the heart also. How shall we differentiate between them? The question arises: How shall we know whether we are following inspiration from God or satanic promptings of the human soul?
Briefly, the point is that in the human material world of phenomena these four are the only existing criteria or avenues of knowledge, and all of them are faulty and unreliable.
What then remains? How shall we attain the reality of knowledge?
By the breaths and promptings of the Holy Spirit, which is light and knowledge itself. Through it the human mind is quickened and fortified into true conclusions and perfect knowledge. This is conclusive argument showing that all available human criteria are erroneous and defective, but the divine standard of knowledge is infallible. Therefore, man is not justified in saying, “I know because I perceive through my senses,” or “I know because it is proved through my faculty of reason,” or “I know because it is according to tradition and interpretation of the Holy Book,” or “I know because I am inspired.” All human standards of judgment are faulty, finite."
`Abdu'l-Bahá:The Promulgation of Universal Peace