A. It is Jesus Himself who speaks so often of the eternal and horrible consequences of human sin. It is Jesus and Jesus alone who emphasizes not only a final judgment but an eternal hell.
B. This passage seems to be an amplification of Mat_16:27. A good parallel passage on a day of judgment is Rev_20:11-15.
C. Jesus is coming again as the Glorified King of Heaven. This is similar to the way the Jews are still expecting Him to come for the first time.
D. The Bible speaks of the certainty of the judgment, but often signifies different agents.