Sentence:  When we become firm enough to stand for those ideals which we know to be right , when we become hard enough to refuse to aid nations which do not permit self-determination , when we become strong enough to resist any more drifts towards socialism in our own Nation , when we recognize that our enemy is Communism not war , and when we realize that concessions to Communists do not <WSD>insure</WSD> peace or freedom , then , and only then will we no longer be `` soft '' . 
Meaning of the word marked with <WSD> tags:  be careful or certain to do something; make certain of something