The Unetanah Tokef prayer is a very special liturgical poem that is chanted on Rosh Hashanah and Yom Kippur.
This link offers the words and an explanation of the Unetanah Tokef. Here is a link to an audio performance by one of histories greatest cantors, Naftali Hertstik.
The Unetanah Tokef peom is based on concepts of Jewish apocalyptic literature which parallel Christian writings based on similar sources.
Whereas Christian liturgy concerning judgment focuses on Revelation and a single "End Times" Judgment, Jews view the High Holy Days as a recurring annual time of Judgment.
You might say we Jews keep doing a rehearsal to get ready for when the Messiah comes. But in essence, the Jews and Christians are both preparing for the "Main Event" each in their own way. Either way, the concept of Judgment Day is meant to strike fear.
FEAR like all God given emotions serves a purpose. I find it interesting that God has given us the emotion of fear to help save us. Whether it is fear of risky behaviors and risky situations which may injure us, or fear of a person who might hurt or kill us, fear serves the purpose to "save us." It offers us an opportunity to change our path. Evidently, Jonah struck enormous fear in the hearts of the people in Nineveh. Failure to listen to our fears can have serious consequences.
Because fear is so powerful, it is often exploited by evil forces. In addition, there are times we need to overcome our fears in order to achieve greatness.
It is fair to say that all of our emotions have to managed. Emotional stability is key to a healthy, happy and productive life overall. I digress ... back to FEAR.
Fear of an imagined death associated with "Judgment Day" serves a more profound purpose. The fear of an eternal life in Heaven or Hell, presents us with a powerful choice about our behavior now. It is the ultimate free will.
Fear of the consequences of "Judgment Day" is "designed" to "Save us." "It is not sinners that God seeks." Fear is God's way of encouraging us to choose life everlasting.
Ironically, the change in behavior that the fear of Judgment helps to create leads to a better life and a better world. Jews and Christians end up in the same place. Heaven on earth ruled by the same King and God.
