Hebrews 4:12
For the word of God is living and active. Sharper than any double-edged sword, it penetrates even to dividing soul and spirit, joints and marrow; it judges the thoughts and attitudes of the heart.
The WTS teaches that a soul is the body or "person" and spirit is the "breath" that animates it. But in the above verse the act of dividing soul and spirit is presented as an equivalent act to dividing joints and marrow. So it would follow that since joints and marrow are two similar objects joined together yet separable, that the author would also consider the soul and spirit to be two similar objects joined together yet separable. If this is the case, the WTS definitions don't really fit, since they consider the spirit to be, not an object, but an abstract animating property.
Inserting WTS definitions renders the verse: "it penetrates even to dividing person and life, joints and marrow." which really doesn't make much logical sense.
But if we assume the WTS definitions are incorrect, then what are the "right" definitions? What then is the difference between soul and spirit?