'Vain' in the Bible

by which also you are saved, if you hold firmly the word which I preached to you -- unless you believed in vain.

If Christ has not been raised, then our preaching is in vain, and your faith also is in vain.

If Christ has not been raised, your faith is vain; you are still in your sins.

Therefore, my beloved brothers, be steadfast, immovable, always abounding in the Lord's work, because you know that your labor is not in vain in the Lord.