Do you think God is happy when men bear false witness on a Christian forum? I mean, this forum is meant to glorify God, so it needs to be carefully protected, and that's not anger.
Bearing false witness is against God.
Perhaps, although the person who doesn't believe in the Trinity may or may not claim to be a Christian at all. If they aren't claiming to be a Christian they probably don't care if something is against God.
There's also the possibility that someone clicked the wrong button, in which case referring to a genuine mistake as "bearing false witness" could arguably be considered to be bearing false witness against the person who made an innocent mistake.
To be honest if I was a non-Christian wanting to troll a Christian board I'd be more inclined to be sure to tick all the right boxes to appear like a fine upstanding member of the community before causing trouble. Maybe that's just me.