Problems often arise when someone else says Well if you really know that is true then prove it to me.' The person either tries to prove it objectively, often without success, or just says I don't have to prove it - I just know it's true.' What they mean is I just believe that it is true'.
Another thing about this first kind of faith is that the person trusts the source of the information. The more they trust the source the stronger their faith. That is why children believe in Santa Claus, and sometimes their friends can't even convince them otherwise, until at around a certain age of understanding they have had enough of hearing their friends' opinions. They have sufficient doubt to ask Mum the question and then they get the real truth. Now they don't believe in Santa anymore. (And how much do they now trust Mum to give them real information?)
The second kind of faith that comes after a statement of belief is made is actually the second phase' of faith. That is - using your will to decide to go on believing that truth or reality against all odds and being faithful' to what you believe. This is becoming a believer' in what you believe. A person can't really say I think I believe that', even though many people actually do this. But a person will either believe something or they won't. They can call thinking they believe something faith' but it will let them down and they will compromise it all the time.
A good example is when a person says that they do not believe that money brings you happiness'. They can say that and feel very noble about it but deep down they would just love to have some more money because maybe it just might make them happier. This is what the Bible calls being double minded' and it goes on to say that a person like this will be unstable in all his ways. This happens a lot, and it can cloud the mind with confusion. It ends up with people saying they believe one thing but acting like they believe something else.
There are other things that are principles of truth that the mind gets to be informed of and it accepts them as a truth' or a belief. It happens to students of mathematics and physics all the time when they discover principles of natural science like gravity or electricity. You don't have to know necessarily how it works but you know it is going to work. Some things like that are clear and easy to believe and to have absolute faith in. But when it comes to some not so clear or obvious things, a decision has to be made as to what one will believe.
Strange things happen when people try to exercise their faith in God. Most people half believe, like the money and happiness thing they have a bet each way. Or they don't trust the source of the truth that is told to them. Or what is worse, they believe in the half truth of somebody else's opinion about God. Or what is worse still, they believe in a wrong opinion about God.
However, the worst thing of all when developing a faith construct about God is not going to the source itself. The problem with faith that concerns God is that people stop short at real faith by trying to believe about God instead of seeking to believe God himself. If you are going to try and believe about God then you had better believe that God is. But even when people believe this, they still don't really go to the source. So it is best to go to God.
Supposing a person has actually decided they want to believe that God is, then where to from there? Supposing they have read and heard about him as the Bible says it, and how Jesus spoke it, and they are informed that God is love, and goodness etc. (that is enough to start with). Then it is a matter of trusting God is who he says he is in his word, the Bible.
By the way, this is NOT faith - yet. When they trust God they will have to wait for the discovery, the revelation, and that comes from The Holy Spirit in this case. They will then be told that God wants to spend time with them and enjoy every moment of their lives with them. They will know that it is not a matter of how good' they are, but how willing they are to trust God to do them good. When they get the information straight from God this way they will know' that God is real, and the truth about Jesus will become the reality of their faith and they will see life in a new way. It is really worth giving a try. The best way to feel gravity is to jump off a low wall it won't kill you!