In "God's Word for Today", David Fry writes:

The reason for miracles is for us to accept Jesus Christ as the true God. The greatest faith, according to Jesus, is the faith of those who simply believe Him and do not ask for signs and wonders. I am reminded that the reason Gideon asked God for a sign was because of the uncertainty of his faith. Our asking God for a sign may reflect an uncertainty in our faith, or it may be our lack of understanding of God’s will. Either way, Jesus made it clear that our faith should not be dependent on Him performing signs and wonders for us.
The nobleman is an example of simple faith... Simple faith believes what it understands and seeks understanding of what it does not know.

Discussion: What is the reason many people think God performs miracles?
Discussion: How can understanding why God performs miracles encourage our faith in Him?
Source: Miracles of Jesus: Adult Teacher's Insights, page 66.