This passage teaches us that the battle between faith and unbelief is a reality in all who are saved by faith in Christ. This battle is so crucial for a Christian disciple to understand and to overcome by believing what Jesus says. Do you look at your circumstances and think they are too dark, too big, even perhaps bigger than God?
All of us have troubles. And if you’re honest, it is very, very hard to believe that God's greatness is greater than your troubled circumstances. Sometimes the harder your troubles are, the harder it is for you to believe that God is in control. You've just entered into the same battle of unbelief that the disciples had in this text.
So don't cast stones at these disciples, who failed to believe in the authority and power Jesus had given them. And be generous toward your brothers and sisters in Christ who are facing this battle. J. C. Ryle says,
“Let us learn that men may understand spiritual things very feebly and yet be true children of God. The head may be very dull when the heart is right. Grace is far better than gifts and faith than knowledge. If a man has faith and grace enough to give up all for Christ's sake and take up the cross and follow Him, he shall be saved in spite of much ignorance. Christ will own him on the last day. So let us learn to bear with ignorance in others, to deal patiently with beginners in religion. Let us not make men offenders for a word, let us not set our brother down as having no grace because he does not exhibit clear knowledge. Has he faith in Christ? Does he loves Christ? These are the principle things. If Jesus could endure so much weakness in His disciples, so we may surely do likewise.”
If you believe that God is sovereign over your troubles and you believe that God is good, you know that God is working in every circumstance of your life for His good purposes if you trust in Him. God is not going to honor doubt. He's going to honor faith. Faith then is at the heart of Christian life and Christian living. It's at the heart of everything. Warren Wiersbe said;
"Faith is not believing in spite of evidence; it is obeying in spite of consequences."
I would add to that..faith is not believing in spite of evidence, it is obeying in spite of your circumstances. Your trouble and trials are gifts to bring you to the fullness of God’s grace. Paul says in Philippians 3.7-10:
“But whatever gain I had, I counted as loss for the sake of Christ. Indeed, I count everything as loss because of the surpassing worth of knowing Christ Jesus my Lord. For his sake I have suffered the loss of all things and count them as rubbish, in order that I may gain Christ and be found in him, not having a righteousness of my own that comes from the law, but that which comes through faith in Christ, the righteousness from God that depends on faith— 10 that I may know him and the power of his resurrection, and may share his sufferings, becoming like him in his death.”