“Blasphemy against the Holy Spirit is to attribute His operations to the opposite spirit, as says Basil the Great. How does one do this? Whenever one sees miracles brought about by the Holy Spirit or any of the other divine gifts in any of his brethren – that is compunction or tears, or humility, or divine knowledge, or a word of wisdom from on high, or anything else that is bestowed by the Holy Spirit on those who love God – and says that this comes from the deceit of the devil. But he also blasphemes against the Holy Spirit who works in them, who says that those who as sons of God are led by the divine Spirit, and perform the commandments of their God and Father, are being deceived by demons. This is what the Jews of old said against the Son of God.
“Like unbelievers and those completely uninitiated into the divine mysteries when they hear anything about divine illumination, or of the enlightenment of soul and mind, or of contemplation and freedom from passion, or of humility and tears that are poured out by the working and grace of the Holy Spirit, the eyes of their hearts are darkened rather than enlightened . . . They audaciously aver that these things come from the deceit of demons . . . To deny that at this present time there are some who love God and that they have been granted the Holy Spirit . . . that they have become gods by knowledge . . . and contemplation, that wholly subverts the Incarnation of our God and Savior, Jesus Christ! It denies the renewal of the image that had been corrupted and put to death, and its return to incorruption and immortality” (Saint Symeon the New Theologian, The Discourses).
