Camper,
Just because someone tells a lie doesn't mean they're a child of the devil. If one of your children are caught in a lie is this how you treat them? Shouldn't we guide them to the truth so they can acknowledge the truth and recover themselves from error? Father Abraham had a slight problem with the truth from time to time. Said his wife was his sister when he felt threatened. God himself had to come down from Heaven and rescue his lying child. How about judge not least we be judged? Moreover we aren't given the knowledge of who is an who is not a child of God. The whole creation is waiting for the revelation of the sons of God, so we don't know who they are yet. We've been told to bless and curse not, and be patient to all men, and even *gasp* love our enemies. Tall order for sure, but the Lord is at hand and is waiting at the door.