I recommend you read this Bible passage as it has a lot for us to learn. Here's a summary:
There was a man with a son possessed with an evil spirit. He said to Jesus, "I asked your disciples to drive out the spirit but they could not!"
The child was brought to Jesus and having explained about his condition since childhood the man said, "If You can do anything, have compassion on us and help us!"
"If You can?" echoed Jesus. "All things are possible to him who believes!"
To which the man responds the immortal words, "I do believe; help my unbelief!"
These words were spoken as a prayer for us. How often do we get into a situation where our faith falters and we're not sure what to believe any more? There is no shame in turning to God and saying honestly, "Help me God ... I don't know what to believe!"
Jesus was impressed by the man's honesty and He healed his son.
But the story does not end there. Later, the disciples asked Jesus, "Why could we not drive out the evil spirit?"
Jesus answered, "This kind cannot come out, except by prayer."
I think what Jesus is teaching us here is true faith. We may pray and pray, but are our prayers accompanied by faith? Do we truly believe that God will answer them positively?
Whilst the disciples of Jesus could not at the time drive out the evil spirit, later on we learn that they too performed many miracles.
In the book of Acts Chapter 3 we read that as Peter and John went into the Temple to pray they met a man at The Beautiful Gate who had been lame all his life. The beggar expected money from the two apostles. Peter turned to him and said, ‘I don’t have silver or gold. But what I have I give you. In the name of Jesus Christ of Nazareth get up and walk!’ and the man was healed.
The important thing to note here is that Peter said ‘in the name of Jesus Christ get up and walk.’
It is God, through Christ, who performs miracles and not the disciples or the apostles or any of us.
Later on in Acts 5 Verse 12 we read that many miracles were performed by the apostles. Sick people lay in the streets so that Peter’s shadow would fall upon them and heal them. And indeed many were healed.
Even today, miracles happen in the name of God through Christ.
All we have to do is believe in an unbelieving world.