This Is God Speaking...

Jesus said the Holy Spirit, the third person of the Trinity, will "teach us all things" and "lead us into truth."  So, how does the Holy Spirit communicate?  How do we know what he is saying? 
Let's take a brief (not complete by any means) look.

Luke seems to have a keen interest in the Holy Spirit, as his gospel account has more to say about the Spirit's work than Matthew or Mark, and nearly as much as John. The book of Acts, probably also written by Luke, describes the Spirit about 60 times, leading the new church just as Jesus said he would.  Quite a few times, someone is said to be "filled with" or "full of" the Holy Spirit, and that leads to some kind of proclamation of God's will.  In Acts 8:29, the Holy Spirit communicates very specifically to Philip, "Go over and walk along beside the carriage.”  In Acts 10, Cornelius has a vision of an angel, and the Holy Spirit speaks to Peter, saying "I have sent" the men who came for him.  In Acts 16, the Spirit leads a group in several ways:  he "prevented them" from preaching in one place; "did not allow them" to go another place; and then Paul had a vision calling them to Macedonia (modern Greece).  So we have several different modes of communication in these chapters.  We may safely assume that the Spirit continues to communicate with us in the same ways.  The Spirit also "breathed" the words of Scripture as we read in 2 Tim. 3:16 and we trust the words of the Bible as it has come to us, to be the words of God.

Words, impressions, pictures, the Scripture, and the words of other Christians, are all part of the Spirit's communication to us.  Then, how do we tell if something is coming from God, rather than just an impression, or a false message?  We are cautioned by the apostle John that we should "not believe everyone who claims to speak by the Spirit. You must test them to see if the spirit they have comes from God" (1 John 4:1).  That testing includes a right understanding of the Bible, and comparing the idea or message to the mind of Christ.  Christ is not divided (1 Cor. 1:13) so any prompting or message we receive from the Holy Spirit will point to Christ (John 15:26) and not encourage strife or division, but work toward harmony. 

This just the briefest overview, and not even a complete one, of the Spirit's methods of communicating to us.  But the point is, the Spirit does communicate, as he is the mind of Christ in us.  So, we should ask God to speak to us, expect to receive direction from him, and be open and receptive to what he has to say.  And then, of course, be obedient!  But that's a discussion for another day.