Everyone has faith. Faith in someone, something, somewhere.
This faith is brought out in their beliefs and their worldview-- the way they see others and the life they live. No matter what they think (be it even atheism or new age) they see something in the world, and through their tired, sin-blocked eyes they try to make sense of this muddled and messed up world.
It is human nature to believe in something, and when the world tells you that there is not God to believe in, you believe them that you must believe in society, in the government, or in yourself. This is totally wrong. Society, and governement are made up of people too-- people who lie, people who mess up and make mistakes.
Somehow still we believe them, and we believe that they can fix things. That they can make things right. And yet they don't. And they let you down time after time, telling you "You aren't good enough without-- [fill in boyfriend, girlfriend, popularity, high paying job, etc.]"....."You can't be great without-- [fill in etc.]".................."Until you believe in yourself, you'll never win"
Even through their lies, they are in a way telling the truth.
We are not good. Human nature is sinful nature-- it is a broken nature that only it's maker can fix. We will never be great without God, and until we believe in him, and truly TRUST him with our futures, we will never win.
It seems simple-- to say we believe. To say we trust. To say "I'm a Christian". But what do we mean? Do we mean? Do we mean we go to church? That we pray to something, someone, up there?
They ask us how we can know for sure, how we can believe in something we cannot see. It is by his grace that we have been saved, and through him, we can see the wonders of God.
That is the truth.
Only God can save us, and we simply must believe. We have to trust-- Truly Trust that he has our back. That no matter what, we must give our lives, and die to ourselves daily. That is the only way we can be made whole. He is the only thing that we can believe in to fulfil our wants and needs.
And all we need is a little faith-- faith the size of a mustard seed. True faith, that we cannot do anything, and He is the only one who can mend our brokenness and help our failed attemps to fly.