If you haven't seen this before (and even if you have) watch this video.
I think there is an important message in that for us as Christians. God is the most significant topic we could talk on and surely he deserves that we present him in a worthy manner. There are segments of the Christian community that put value on doubting everything and scorn the idea of being able to say much for certain about God. I certainly wouldn't wish to argue for arrogance or that we will know everything with perfect certainty. But for those things we can know, we should be doing out best to speak with conviction. As someone who tends towards being a little shy, it is hard but I pray that with God's grace I may be able to speak of him with the conviction and passion he deserves.