In the book of Hebrews, the Bible defines faith as "the assurance (the confirmation, the title deed) of the things (we) hope for, being the proof of things (we) do not see and the conviction of their reality" (Hebrews 11:1, Amplified). We are hoping to reach heaven, a world we cannot see, and faith gives substance to our expectations.
Faith can be a title deed to things we cannot see. For example, suppose there is a lot in a Florida resort, which you have never seen. A salesman comes to you and says, "I have a lot in this plat, and if you will give me $10,000, I will give you a deed to it." So you give him the money, and he gives you the deed. The moment the deed transfers, you own the property. You might not see it for many years, but you know it is yours, because the title deed has conferred all ownership privileges upon you. From that moment on, you can begin to enjoy it.
That is faith. It is the title deed to things we cannot see. Faith is an attribute given by the Spirit of God that enables us to reach into God's invisible world and take possession of that which we cannot see.
Faith is one of the fruits of the Spirit, and this means that it grows naturally for those who belong to God (see Galatians 5:22). The Bible says the testing of faith produces patience, which means we can develop a stronger faith by working on it (see James 1:3). If we exercise faith, just as we would exercise a muscle, it will grow. The more we walk in faith and appropriate things by faith, the more our faith grows. We get to a point where we say, "If God can do what I have experienced, then surely He can do something more." Our faith will grow as we use it, whether it is faith for healing or for family unity or for finances or even for the conduct of national affairs.
There is also what is called a manifestation, or a gift of faith (see I Corinthians 12:7-9). This is a supernatural enablement of faith that God gives when it is especially needed.
This supernatural faith is the kind of faith that can move mountains, provide divine protection from danger, or provide for an unusual financial need. Faith can be something that is continuously growing through use, or it can be something that comes instantaneously as a gift from God.