Faith in Christ -- the definition faith outlined by His teachings -- means being so sure of something that's it like you already have it, even though it's not here yet. It's like having the deed to a property mailed to you even though you haven't seen the property yet -- as I heard recently at church.
But sometimes, for one reason or another, we get burned out spiritually, and our faith -- our confidence and trust in God -- gets weak and flimsy.
If you've ever been in that situation, or if you're there right now, here's a small piece I wrote on the topic (in greater detail) for RockinGodsHouse.com. I hope it blesses you: