The apostles said to the Lord, ‘Increase our faith!’ The Lord replied, ‘If you had faith the size of a mustard seed, you could say to this mulberry tree, “Be uprooted and planted in the sea”, and it would obey you.
(lectionary, New Revised Standard Version)
Jesus uses the example of a mustard seed a few times in the Gospels, mostly about the Kingdom of God. In Matthew's Gospel for instance he says:
But Jesus also uses the mustard seed as an example of the amount of faith needed to produce a miracle. In Matthew's Gospel he says, if we have enough faith we can "move a mountain from here to there" (Matthew 17.20). Today, in Luke's Gospel, Jesus uses the tiny mustard seed again, but with a quirkier example, which appeals to me since I remember my desire to move the mulberry tree from outside the Old Palace in Worcester, under which I had parked my car. It took days to remove the staining from the large squashy mulberries that landed on it that day. Sadly to say I didn't have enough faith to move the tree!
Many Christians will identify with this request for more faith by the disciples, as we too often battle with our faith. But faith is not something that you either have or don't have - we all have the potential for faith, but some people’s grows more than others. It's like a seed that's planted, which needs to be fed and watered to allow it to grow. Just as when we learn to swim we discover that we're not actually going to drown, and we can take off the armbands, so with Christian faith, trying it out, actually means our faith will continue to grow.
Lord Jesus Christ,
help us to have more faith in You,
and in Your teaching.
Teach us to stop wallowing in the shallows
and embrace the deeper waters.
Increase our faith that we grow stronger,
and able to fulfill our true potential
as Your sons and daughters.
Amen.
I found this article on growing faith, helpful:
Or you could play this: