IS KILLING FORBIDDEN?

Exodus 20:13  Thou shalt not kill. (KJV) Exodus 32:27  And he said unto them, Thus saith the LORD God of Israel, Put every man his sword by his side, and go in and out from gate to gate throughout the camp, and slay every man his brother, and every man his companion, and every man his neighbour. (KJV)

There are other cases of God ordering the Israelites to kill, but I'll just show this one (which is the one most often used by those trying to claim contradiction).  In its original Hebrew, the exodus passage commands us not to murder.  Not all killing is murder.  In the case presented here, a large group of Israelites were trying to lead Israel away from God.  Had they been allowed to live, all of Israel would have perished.  God was essentially ordering Israel to prune itself of a branch which would have destroyed it, which is very justified.  Not a contradiction.