The [[heresy]] of Jehovah's Witnesses is clearly presented in their books; some of which are the following:
*Their book "''The Truth that leads to eternal life''," P. 24: [The Holy Spirit is not a Person, but God’s effective Power.]
*Their book "''Let God Be True''", P. 113: [The allegation of the clergy that the Holy Spirit is a third Spiritual Person, is an allegation based on a weak basis. It is the result of bad translation of the Greek original text, giving a word that means Person. But actually the origin means "breeze" or "wind", for as the breeze or the wind is invisible so also is God's Spirit. Whenever God’s Spirit comes upon a person, that person receives an authorization from God to perform a certain work. The Holy Spirit is the Power of God Almighty and Invisible. He is the Power that motivates God's servants to do His will.]
To sum up, their denial of the Hypostatic Nature of the Holy Spirit is a part of their denial of the Three Persons. Accordingly they deny the doctrine of the Holy Trinity.