What does Matthew 25:43 mean?
Jesus is condemning a large group of people to eternal fire, originally intended for Satan and demons (Matthew 25:41–42). This group of people rejected faith in Christ; they are not among those "elect" who came to faith in Christ (Ephesians 4:1; Matthew 24:22; Mark 13:27; Romans 11:7; Titus 1:1). This lack of faith in Christ is proven by their actions, or lack of action (John 14:15).Christ holds responsible those who didn't provided for His needs. As with the righteous, the wicked ones will echo Jesus' judgment as a question. By the end times, the majority of mankind will never have seen Jesus in person, leading them to wonder how their actions can be applied to Him? Christ will give the same explanation offered to the first group: He takes loving service very personally (Matthew 25:40).
For those in this second category, this question also comes across as an attempted excuse. Often, confronted with failure to do right, our instinct is to say something like "had I known someone would care, I would have…" Whether or not such claims are honest is irrelevant; failure to do what God asks of us is always a sin (James 4:17). Claiming that we would have done for Jesus what we refused to do for "normal" people isn't any better (James 2:1).