Albert Barnes Commentary Matthew 25:12

"But he answered and said, Verily I say unto you, I know you not." — Matthew 25:12 (ASV)

I know you not. You were not in the company of those who attended me to the marriage feast, and are unknown to me. Applied to professing Christians, having only a profession of religion, but no real piety, it means I know, or acknowledge you not as Christians. I do not approve of you, or delight in you, or admit you to be my friends. The word "know" is often used in the sense of approving, loving, and acknowledging as real friends and followers. See Matthew 7:23, Psalms 1:6, 2 Timothy 2:19, 1 Thessalonians 5:12.