Jesus asks this question so that his hearers will stop thinking that God is slow to help those who call to him for justice and will understand that the real problem is that they do not truly have faith in God. Alternate translation: "when the Son of Man comes, you need to be sure that he will find that you truly have faith in him." or "when the Son of Man comes, he will find few on earth who believe." (See: [[rc://en/ta/man/translate/figs-rquestion]])