We see that it is the work of the H.S. to convict sinners when they hear the man of God preach (6:10), and it is through the Spirit that prophets can prophecy (11:28).
The primary work of the H.S. is empowering believers to be an effective witness for the Lord Jesus Christ (1:8). The filling of the H.S. brings “utterance” (1:11; 2:4; 20:23), boldness (4:8; 31). The subject matter of the utterances is the “wonderful works of God” (2:11). We see this manifested in Stephen’s martyrdom (6:5, 10; 7:55). It was a Spirit-filled Paul that rebuked Elymas (13:9). All God desires for us is to be yielded to Him. Yielding (i.e. obedience to God and His Word) is the only requisite found in the entire book wherein God is pleased to grant the power of the Holy Spirit (5:32). Indeed the filling of the H.S. is truly manifest when the Spirit Himself is doing the witnessing through Christians that are yielded to God. Surrendered Christians are just vessels used of God (20:23). Even Christ was anointed with power (10:38), how much more do we need the power of God in our lives? The filling is paralleled with other virtues such as godliness (11:24), honesty, wisdom, faith, and even joy (6:3-5; 13:52). No wonder the Charismatic movement falsely claims a “fullness of the Spirit” it is because they want to be thought of as being godly. The difference is that godly Christians don’t pretend to be godly, they just are. Furthermore, godly Christians bring glory to God and not to themselves.
There is also the indelible mark of inspiration attributed directly to the Holy Spirit in the first and last chapter of Acts (1:16 and 28:25). The Bible is certainly a Spirit-authored book. Divine causality (God, the H.S.) moved upon “holy men” to create the Sacred Scriptures. The fact that we have God’s Words in our hands is because of the powerful and miraculous work of the H.S.