The idea that Scripture is conveying here is that we as believers are sharing or partaking with the Holy Spirit in something. We are united to the Holy Spirit and through Him, we are sharing in something. But what might that something be? What is this life or experience that the Holy Spirit is personally bringing us to be part of?
The Holy Spirit is always at work in us, He works with a strong desire to produce the character and life of Christ in us. He works to equip us to serve the Lord; to refine us and to help us to become more spiritual and able to live a more holy life. He enables us to examine our hearts; to look at our words; our behaviour, and our manner of living. The Holy Spirit convicts and confronts us. He helps us by giving us an ear to hear, read and understand the Bible, so that it 'speaks' to us. These things, and so much more, are part of the Holy Spirit's work in our daily spiritual pilgrimage.