Is killing always wrong?

The sixth commandment: ‘Thou shalt not kill.’

Thou shalt not kill.

Whoever kills a man is to be put to death; a killing that was not planned is treated differently from one done with guile.

He that smiteth a man, so that he die, shall be surely put to death. And if a man lie not in wait, but God deliver him into his hand; then I will appoint thee a place whither he shall flee. But if a man come presumptuously upon his neighbour, to slay him with guile; thou shalt take him from mine altar, that he may die.

After the golden calf, Moses sends the Levites through the camp to slay; about three thousand die.

Then Moses stood in the gate of the camp, and said, Who is on the Lord’s side? let him come unto me. And all the sons of Levi gathered themselves together unto him. 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. And the children of Levi did according to the word of Moses: and there fell of the people that day about three thousand men.

A man who gathers sticks on the Sabbath is stoned by the congregation at the Lord’s command.

And while the children of Israel were in the wilderness, they found a man that gathered sticks upon the sabbath day. And they that found him gathering sticks brought him unto Moses and Aaron, and unto all the congregation. And they put him in ward, because it was not declared what should be done to him. And the Lord said unto Moses, The man shall be surely put to death: all the congregation shall stone him with stones without the camp. And all the congregation brought him without the camp, and stoned him with stones, and he died; as the Lord commanded Moses.

Samuel tells Saul to destroy Amalek for its attack on Israel after the exodus.

Thus saith the Lord of hosts, I remember that which Amalek did to Israel, how he laid wait for him in the way, when he came up from Egypt. Now go and smite Amalek, and utterly destroy all that they have, and spare them not; but slay both man and woman, infant and suckling, ox and sheep, camel and ass.