We need to look at the whole story to understand the meaning of the verse, the father first addressed Jesus as master and if you could do anything please help us, clearly showing his lack of understanding of who Jesus was.
Then we see Jesus rebuking the father rather than healing the son, including him in the generation that should of know from the Daniel 9 prophecy it was time for their Messiah to come, after that we see Jesus asking the father a question that was His M.O. to reveal He could read his heart, like he did with Nathaniel and the woman at the well, he indirectly asked the question of how did the boy become demon possessed, knowing it was the father's fault (children are protected from demon possession unless the parents are playing with things they shouldn't be), the father, like Nathanial, the woman and all of us who believe were illuminated and we see the father addressing Jesus as Lord Matt 16:17, then Jesus teaches Him about faith and we come to our verse.
We are all given faith the size of a grain of mustard Eph 2:8 when we believe, after that we are to grow in faith, so there are a couple of ways this verse can be useful to us, first we pray and ask the Lord to increase our faith, so He puts us in situations where we must exercise our faith and second we have faith in God and see Him working in the lives of others, but we don't have the faith He will work in our lives, this is a lesson in the Sovereignty of God and we believing we are the same and equal in His sight as are all of His children and He blesses as He wills, the lesson to be learned is Godliness with containment is great gain, if God blesses us that is great and if He chooses not to then that is great to, He is Sovereign.
Now the subject of faith is very important for us because the Ho;y Spirit inspired Paul to write three commentaries on Hab 2:4, the just live by faith, Romans teaches who are just, Galatians teaches how to live and Hebrews teaches about faith, so why is faith so important, because it is our mode of locomotion for all of eternity, how much faith we have is how far we will be able to travel, take the story of Jesus with the disciples on the road to Emmaus, after revealing Himself to them He disappeared and reappeared in Jerusalem that same night and entered the house through a sold rock wall in His new Heavenly body, just like the ones we will receive at the Rapture, Jesus was giving us a hint of what awaits for us in heaven, ...as we think where we will want to go and by faith be there.
Blessings
Gene