I am the good shepherd; I know my sheep and my sheep know me . . . John 10:14
The witness of the Spirit is a sacred inner thing which cannot be explained. It is altogether personal and cannot be passed from one to another. Deep calleth unto deep at the noise of God’s waterspouts, and the outward ear cannot hear what it says. Much less can the worldly onlooker know what is taking place. The Spirit whispers its mysterious Presence to the heart, and the heart knows without knowing how it knows. Just as we know we are alive by unmediated knowledge and without recourse to proof, so we know we are alive in the Holy Spirit. Our knowledge is by immediate cognition altogether independent of inference and without the support of reason. The witness is in the hidden regions of the spirit, too deep for proof, where external evidence is invalid and “signs” are of no use.
When all is said, it may easily be that the great difference between professing Christians (the important difference in this day) is not between modernists and evangelicals but between those who have reduced Christianity to an intellectual formula and those who believe that the true essence of our faith lies in the supernatural workings of the Spirit in a region of the soul not accessible to mere reason.
by A.W. Tozer