It is a simple, short and straightforward question. It was asked of one man but is universal and is asked of all men and woman.
“Who do you say I am?” (Mathew16.15)
If you answer as did Paul, immediately in his case, “You are the Christ, the Son of the living God.” then eternal life is yours, no matter the ups and downs of this life.
It's a matter of faith and trust for which in return undeserved Grace is given.