I'm a native-level English speaker but the meaning of this phrase is not obvious to me.
Context (emphasis mine):
Every gun that is made, every warship launched, every rocket fired signifies, in the final sense, a theft from those who hunger and are not fed, those who are cold and are not clothed.
My first guess is that it means the theft is final because it destroys economic value irreversibly, but I'm not sure whether it's correct. Another guess is that it means that it will be judged as theft in the eyes of God (i.e., the final judgement).