For our gospel came not unto you in word only, but also in power, and in the Holy Ghost, and in much assurance. 1 Thess. 1:5.
There's a big difference between simply speaking words and having the Holy Spirit make those words effective by His power. "Only when the truth is accompanied to the heart by the Spirit will it quicken the conscience or transform the life. One might be able to present the letter of the Word of God, he might be familiar with all its commands and promises, but unless the Holy Spirit sets home the truth, no souls will fall on the Rock and be broken."--The Desire of Ages, p. 672.
The first work of the Holy Spirit is His convincing work. Our greatest need is to realize our need of salvation. How many people who have been born and reared in religious circles, and are third-and fourth-generation church members, have had this lack as one of their problems. Some people say, How can you recognize your need if you have never been out in the world? How can you realize your need if you have never known anything else but going through the regular routine of religion and formal worship? The Holy Spirit is responsible for bringing each person to realize his need, and although He can make use of the troubles and sorrows of sin to point it out, He can also work in the heart by uplifting Jesus and showing us how far we fall short of His standard, even when everything is going well.
Sometimes we try to help other people realize their need by pointing out to them their need. But if we are working apart from the inspiration of the Holy Spirit, who alone knows the proper timetable for each one, we end up with zero. On the other hand, we can talk about the Holy Spirit, and how it is His work to bring conviction, and then sit back and wait for Him to work. But the Holy Spirit wants to use us, to control us, to work through us, in order to reach other people. Jesus told His disciples that He wanted to send the Comforter to them. The Holy Spirit is sent to us, to live in us, and by cooperating with Him we can be used of God to reach other hearts. God intends to work through us. It is not His purpose for us to work without the Holy Spirit, nor for the Holy Spirit to work apart from us. We are to cooperate with Him.