Man, saved or not, is a composite of body and soul. Potters clay infused with a spirit. When you read the Bible you do so with fleshly eyes even though it is the inner eye that “sees” the truth. When you speak to others it is with a fleshly tongue that communicates what you know to others.
Unsaved man does not have the Holy Spirit indwelling him. ANd that is where spiritual discernment comes from.