In Acts 5:1-11 we have the account of Ananias and Sapphira. As previously alluded to, this is an important text for demonstrating truths about the Holy Spirit: first, that he is God (Acts 5:3-4). Secondly, the passage forms part of the evidence for his personality—as opposed to the view that the Holy Spirit is just some sort of force, energy, etc. The support for his personality is based upon the fact that he can be lied to. You can lie about things, but it is not really possible to lie to a thing.
But the passage also demonstrates one of the difficulties facing Trinitarian study. In Peter’s examinations of the wayward couple he speaks of their lying to the Holy Spirit (5:3); lying to God (5:4); and testing the Spirit of the Lord (5:9). So we have reference to Holy Spirit, God, and Spirit of the Lord. I think Peter is speaking of the Holy Spirit in all three. But perhaps one might say God refers to the Father and Spirit of the Lord is another way of saying Spirit of Christ—a title Peter does use in 1 Peter 1:11. In either case, we see the fluidity of terminology applied to the Trinity. I am trying to be attentive in searching the Scripture for Trinitarian references: attentive, but conservative. So I do not see a reference to the Trinity in Acts 5:1-11; though I suppose it is possible some others might see it.
Acts 5 does contain a clear reference to the Trinity though:
But Peter and the apostles answered, “We must obey God rather than men. The God of our fathers raised Jesus, whom you killed by hanging him on a tree. God exalted him at his right hand as Leader and Savior, to give repentance to Israel and forgiveness of sins. And we are witnesses to these things, and so is the Holy Spirit, whom God has given to those who obey him.” Acts 5:29-32
After yet another arrest and a miraculous release from prison, Peter and John are corralled again by the religious authorities and scolded for their audacity to preach in the name of Jesus (5:28). Peter’s response is typically Trinitarian. I say that because it seems every time Peter opens his mouth in the book of Acts he speaks of the Trinity.
Why would the apostles continue to preach in the name of Jesus while under the threat of imprisonment and even death? Peter’s answer is powerful: because that is what the Trinity has done and is doing. The Father resurrected and exalted the Son so people would repent and find forgiveness. The Holy Spirit is witnessing to these things: both autonomously and through the followers of Christ that have obeyed the Father’s call to faith. The Trinity is intimately, individually, and indissolubly pledged to the salvation of a people. How can that people do anything else than proclaim the work of salvation the Trinity has accomplished, is accomplishing, and will accomplish?
Believers should be reminded of Mathew (28:18-20) and Luke’s (Acts 1:6-8) account of the Great Commission. Both are deliberately Trinitarian. We proclaim salvation to the nations because of the Father’s exaltation of the Son and the Spirit’s witness to the Son. This is the work of the Trinity. We joyfully join in their work.