Believe....Act

"To believe something is to ACT as if it were true."

I can't get this quote out of my mind. I can't escape it or get rid of it. My pastor used it a long while ago in a sermon and it's still haunting me. I'm convinced that the holy spirit is trying to tell me that I need to really get this one.
It's pretty interesting, this quote, because for a long time I've kind of been thinking along those lines, and this quote just sort of wraps it up for me and puts a pretty little bow on it. I've struggled with this concept for some time now and I am excited to really look at it, study it and see what I can learn from it.
Here's what I'm thinking so far...if we REALLY believe in God, REALLY believe in Jesus Christ, REALLY believe that he came as the Messiah to save the world, REALLY believe that he was crucified for us, died for us and conquered death by rising again, REALLY believe that by believing in him and following him that we are forgiven for our sins and live in freedom, REALLY believe that we have eternal life and are truly, truly, truly saved and free to just love and serve our neighbor in the name of Christ.....then we should be ACTING like we BELIEVE it. If we REALLY, REALLY, deep down REALLY believe all of these things as the ultimate and sure, bottom line truth, then we should be changed, different, alive, energized, living freely, loving abundantly, sharing all of our possessions and time and talents, happy, joyful, peaceful, sure of our salvation and eager to share this new found freedom with anyone and everyone, especially those we love.
If we REALLY believe that we are saved, that we are ourselves going to conquer death and live eternally with Christ, then why are we anxious, stressed, grumpy, lazy, clinging to material things and social status, worried about what others think, afraid to just be ourselves and accept who we are in God's eyes, why aren't we constantly singing and dancing and rejoicing in our freedom, why aren't we helping each other more, out saving the world and trying to convince everyone to turn to Christ so that they too can live eternally?
If we REALLY believe in God, why aren't we ACTING like it?