Jonathan Edwards distinguishes so clearly in his little sermon “The Reality of Spiritual Light” between real enlightenment for the believer and (any) light that might be given to the unbeliever. He says,

“In this spiritual light…(there is) a true sense of the divine and superlative excellency of the things of religion; a real sense of the excellency of God and Jesus Christ, and of the work of redemption, and the ways and works of God revealed in the Gospel. There is a divine and superlative glory in these things; an excellency that is of a vastly higher kind and more sublime nature, than in other things…He that is spiritually enlightened truly apprehends and sees it or has a sense of it. He does not merely rationally believe that God is glorious, but he has a sense of the gloriousness of God in his heart. There is not only a rational belief that God is holy, but there is a sense of the loveliness of God’s holiness.”

(Works, Vol. 2, p. 14)

Such a sense can only come as a result of the regenerating work of the Holy Spirit. The reality of it is sweet indeed.