Dougan Clark preaches about the role of the Holy Trinity in the sanctification of a human soul, emphasizing the distinctiveness of the Holy Spirit as the Sanctifier. The mysterious work of sanctification is a divine process that involves the Holy Ghost purifying the heart through faith, leading to a complete cleansing from sin. The apostles Peter, John the Baptist, Paul, and others highlight the Holy Spirit's crucial role in sanctifying believers, emphasizing the need for faith in the truth for this sanctification to occur.

As already intimated all the persons of the adorable Trinity are concerned in the work of entirely sanctifying a human soul. And this is naturally to be expected, because God is one Trinitarianism is not Tritheism. In essence one, in personality three, such is the revelation of Holy Scripture in regard to the eternal Godhead. The Bible reveals the fact, but does not reveal the how. We bow in adoring gratitude and love before an incomprehensible mystery, and rejoice in believing even without understanding. Now the Holy Spirit is regarded by nearly all Christians as distinctively and specially the Sanctifier, “The renewing of the Holy Ghost which He shed on us abundantly through Jesus Christ, our Saviour,” is spoken of in the epistle to Titus in direct connection with the “washing of regeneration,” and seems intended to be experienced just after it. Possibly the renewing here spoken of, may signify only the change of heart wrought by the Holy Ghost at the new birth, but possibly, also, the apostle had in mind the entire cleansing of the heart from sin. And in that case the renewing need not be any more gradual or progressive than the washing, which all admit to be instantaneous. Peter, in describing, to the Church at Jerusalem, the occurrences which he had witnessed at the house of Cornelius in Cesarea, used this language: “And God which knoweth the hearts, bare them witness, giving them the Holy Ghost, even as He did unto us, and put no difference between us and them, purifying their hearts by faith.” Evidently here the chief of the apostles gives us to understand that the giving of the Holy Ghost, and the purifying of the heart by faith, are co-instantaneous and identical experiences. And if this be so, the Holy Ghost, who is a Divine person, and not a mere influence, must be the effective agent in purifying the heart, that is to say, it is He who by His Divine energy sanctifies us wholly. And with this agree the words of John the Baptist: “I indeed baptize you with water, unto repentance, but He that cometh after me is mightier than I, whose shoes I am not worthy to bear. He shall baptize you with the Holy Ghost and with fire.” For what purpose is this fiery baptism with the Holy Ghost? Most certainly that it may consume the inbred sin of our nature, as fire consumes the chaff, or destroys the alloy that the gold may be left pure. Paul in his epistle to the Romans uses the following language, viz: “That I should be the minister of Jesus Christ to the Gentiles, ministering the gospel of God that the offering up of the Gentiles might be acceptable, being sanctified by the Holy Ghost.” This great apostle was the first to clearly understand the perfect equality between Jew and Gentile in the gospel of salvation, and as he made hundreds of Gentile converts in His extensive missionary journeys, and offered them up with their own consent and co-operation in entire consecration to God, they were sanctified by the Holy Ghost. The same apostle says to the Thessalonians, “We are bound to give thanks always to God for you, brethren, beloved of the Lord, because God hath from the beginning chosen you to salvation through sanctification of the Spirit and belief of the truth.” This is the true election and the true salvation, a salvation from sin, through sanctification of the Spirit and this is to be obtained by faith. And the apostle of the circumcision uses language very similar in addressing the Jewish Christians who are scattered abroad, and whom he addresses as “Elect according to the foreknowledge of God the Father, through sanctification of the Spirit, unto obedience and sprinkling of the blood of Jesus Christ.” Comparing these two citations we observe again, that the blood of Jesus Christ is the ground of our sanctification, and by a continuous sprinkling we may have a continuous cleansing, and also that the Holy Spirit is the effective agent in applying that precious blood, and in sanctifying our souls, on condition that we believe the truth. God help all Christians to be not faithless, but believing.