Who the Holy Spirit is determines what the Holy Spirit does. Who is the Holy Spirit? aims to help people see who the Holy Spirit is through Scripture's description of him, offering biblical insights into the identity of the third person of the Trinity. With consideration for the Spirit's identity derived from both Old and New Testament accounts, author Malcolm B. Yarnell focuses on identifying characteristics of the person of the Holy Spirit himself, rather than discussing the work of the Spirit solely in the context of salvation and sanctification, or external signs and wonders.