In this quote C. S. Lewis speaks to the reality of the supernatural:
For me the Christian doctrines which are “metaphorical” - or which have become metaphorical with the increase of abstract thought - mean something which is just as “supernatural” or shocking after we have removed the ancient imagery as it was before. They mean that in addition to the physical or psycho-physical universe known to the sciences, there exists an uncreated and unconditioned reality which causes the universe to be; that this reality has a positive structure or constitution which is usefully, though doubtless not completely, described in the doctrine of the Trinity; and that this reality, at a definite point in time, entered the universe we know by becoming one of its own creatures and there produced effects on the historical level which the normal workings of the natural universe do not produce; and that this has brought about a change in our relations to the unconditioned reality.
The resurrected Jesus Christ sent as He promised the Holy Spirit to indwell believers in repentance, bringing “a change in our relations to the unconditioned reality,” to the Holy Spirit, to God the Father, by His grace through Jesus Christ.