ANSWER: This excellent version gives the idea not of the separating, but of the pervasive and penetrating power of God's truth accompanied by the illuminating and purifying spirit. In the priestly examination of an animal for sacrifice, the outside was examined and then the flesh after it was skinned, and finally the backbone was cleft with a cleaver from end to end, dividing the spinal cord so as to detect the least speck of disease. The writer of this epistle uses this priestly practice to illustrate the office of the Holy Spirit in the detection of inward impurity.
– Steele's Answers pp. 77, 78.