Perhaps you could "witness", take an opportunity to show how the core of Christianity IS in keeping with Jesus' words in the Synoptic Gospels. "I am the way, the light..." etc. in John 14:6 forms the basis of the soteriology. Sure Jesus was not as clear on his homoosiouosness with God but it was pretty clear there that he was the savior.
Jesus other commands to not live by the sword, or not worship money, all that can be thrown away by many Conservative Christians, but the essence does seem to be there in the Gospels.
Try that approach rather than just being a raving bastard. I'm sure it will be a better "witness". No matter how you feel about the other poster (remember to "turn the other cheek"), just do your job as a Christian. It's your "Great Commission".