Apart - James 2:26

James 2:26 ESV 

For as the body apart from the spirit is dead, so also faith apart from works is dead.

James sums up the matter in this sentence. Life is the opposite of death. The spirit animates the body and when removed leaves body dead. Spirit is something on the inside which manifests on the outside. Most can identify and discern between a body that is alive or dead. 

Likewise, faith animates a body into new life. The absence of works reflects faith that is dead. Works are fruit of the Spirit. Faith that has life is evidenced by the presence of the Spirit. That faith is discernible because it is alive. 

Limbs apart from the vine wither and die.