Jesus illustrates faith to us by using the parable of the mustard seed.
Matthew 13:31-32 (NKJV)
Another parable He put forth to them, saying: “The kingdom of heaven is like a mustard seed, which a man took and sowed in his field, which indeed is the least of all the seeds; but when it is grown it is greater than the herbs and becomes a tree, so that the birds of the air come and nest in its branches.”
Faith can start of as small as a mustard seed, but it has the potential to grow into a beautiful and massive tree. We will get into more detail about how we can grow from a tiny little seed into a great big tree, a little bit later.