Two E G White quotes, Gary quoted, when put together - make it so clear:
"There is but one power that can break the hold of evil from the hearts of men, and that is the power of God in Jesus Christ. Only through the blood of the Crucified One is there cleansing from sin. His grace alone can enable us to resist and subdue the tendencies of our fallen nature." 8T 291 (1904)
"Sin could be resisted and overcome only through the mighty agency of the Third Person of the Godhead, who would come with no modified energy, but in the fullness of divine power." DA 671 (1898)
Put these two quotes together and it is so clear that the Holy Spirit / Holy Ghost / Third Person of the Godhead, is "the power of God in Jesus Christ" - it is the combined spirit / power / mind of God and His Son.
I also like the quote:
"Christ tells us that the Holy Spirit is the Comforter, and the Comforter is the Holy Ghost, "the Spirit of truth, which the Father shall send in My name." "I will pray the Father, and He shall give you another Comforter, that He may abide with you for ever; even the Spirit of truth; whom the world cannot receive, because it seeth Him not, neither knoweth Him: but ye know Him, for He dwelleth with you, and shall be in you" [John 14:16, 17]. This refers to the omnipresence of the Spirit of Christ, called the Comforter." 14MR p.179 (Letter7,6-11-1891)
Is that clear or is that clear?