True Faith Moves Both Heart and Lips
Luke 12:8 (ESV) … “And I tell you, everyone who acknowledges me before men, the Son of Man also will acknowledge before the angels of God…”
Jesus issued two warnings in order to urge his followers to confess him. First, “I tell you, whoever acknowledges me before men, the Son of Man will also acknowledge him before the angels of God. But he who disowns me before men will be disowned before the angels of God” (vv. 8, 9).
According to Paul, the inception of authentic faith in Christ involves verbal confession of him: “That if you confess with your mouth, ‘Jesus is Lord,’ and believe in your heart that God raised him from the dead, you will be saved. For it is with your heart that you believe and are justified, and it is with your mouth that you confess and are saved” (Romans 10:9, 10). True faith always moves from the heart to the lips. On the other hand, a lack of desire to confess Christ before others is a warning alarm—do we really have faith? An unwillingness to bear witness may mean we have fooled ourselves—we are not truly children of God.
This is a great concern to Jesus. He said, after Peter’s great confession, “If anyone is ashamed of me and my words, the Son of Man will be ashamed of him when he comes in his glory and in the glory of the Father and of the holy angels” (Luke 9:26). And the one who gave himself for us says it here again. We must confess him—always!
Jesus’ famous and often misunderstood second warning was about blasphemy: “And everyone who speaks a word against the Son of Man will be forgiven, but anyone who blasphemes against the Holy Spirit will not be forgiven” (v. 10). What is blasphemy against the Holy Spirit? Helpfully, we know from Matthew and Mark and from an earlier passage in Luke that Jesus made this declaration after the scribes and Pharisees had attributed his cures to Beelzebub, the prince of devils (Matthew 12:31, 32; Mark 3:28, 29; Luke 11:14–26). In other words, they attributed the mighty work of the Holy Spirit to Satan. Jesus said there is no forgiveness for this.
On this occasion Jesus introduced the thought with the assertion that sins against him can be forgiven. This does not mean that such sins are a small thing (see the preceding verses). But sin against his august person can be forgiven. Some blaspheme Christ but then repent—their blasphemy is not their final word. Many blasphemers have been saved. But those who blaspheme the Holy Spirit by attributing his work and witness to Satan are damned. This blasphemy is not so much a matter of blasphemous language but of a conscious, persistent, wicked rejection of the Spirit’s witness. It is a setting of the mind against the Spirit of God.11
These words were meant to bring a sobering shock to the hearts of those who had been toning down their confession in hopes of escaping the impending trouble. Those with true faith would hear the wake-up call and continue their good confession.
 Hughes, R. K. (1998). Luke: that you may know the truth (pp. 41–42). Wheaton, IL: Crossway Books.