What makes someone truely Christian? There is only one answer (v3b)
To be truely Christian is to be convinced that Jesus is Lord.
1. The Holy Spirit at work. (v3) Jesus spoke about the role of the Spirit revealing who Jesus is. Not just saying the three words, but rather a deep seated conviction that changes your life. People in Paul's day said there were many lords, but the Christian rejected them all, and this could be a costly confession. It confronts people.
2. True Spirituality is fruit of God's Spirit. This confession is the one thing we all share. Chapters 12-14 introduce a new issue of 'spiritual gifts'. The Corinthians were wrong in understanding of Spiritual gifts. Spirituality is about our confession and glorifying Jesus as Lord. It is not about us, it is about Jesus (v3). The greatest miracle is new birth and is most wonderful.
3. What and how of Christianity. It is shaped by these 3 words (compare Roman 10:9). It is the work of the Spirit that we hold this conviction, and continue to live by it. Similarly for our Church and its leaders.
