The word “useless” is a pretty strong term. The English word means to be “of no use; not serving the purpose or any purpose; futile; of no practical good.” Has anyone ever told you that your efforts were “useless”? What if God told you that your efforts were “useless”?
The Greek word often translated “useless” is used to describe idols (Acts 14:15), “foolish controversies” that Christians must avoid (Tit. 3:9) and our “faith” if “Christ is not risen” (1 Cor. 15:17). Truly, it is being said, that such things are “of no use, not serving the purpose, futile.” And we would expect the New Testament to express such. But notice one other use.
“If anyone among you thinks he is religious, and does not bridle his tongue but deceives his own heart, this one’s religion is useless” (Jas. 1:26). I may “look good” as a Christian (in my eyes) and think “all is right” in my relationship with God, but if I do not bridle my tongue, my outward actions of devotion are “useless.” “Dear Lord, please help me to control my tongue!”