Absolute Choice

Absolute Choice (絶対選択肢) is a curse created by God for certain people.

Summary
"Absolute Choice" is a nickname given by Kanade. As the name suggest, once the choice is made, the cursed one will be forced to carry out his/her selected choice against their own will. The choice can even alter the reality around the cursed one to make them comply with the choice, such as changing sex, making them into inanimate objects, and causing wide spread chaos.

Appearance
In the novel and manga, the choice appears to be a simple screen with the letter "Choose:" (選べ：) and the two options seen below. While in the anime, the command to choose didn't appear but the choices appear everywhere around the cursed character.

How to Prevent the Curse
According to Seira, one must have truly fallen in love with someone.

How to Lift the Curse
It is often mentioned that one must complete all the missions given by God.

According to Seira Kokubyakuin there is another way to lift the curse, the affected person must fall in love with someone and the curse will vanish.

Helpers
These are servants of God, probably Angels who are sent to those affected by the Absolute Choice, to help them get rid of this curse.

It is mentioned that once the curse has been lifted the helpers will return to their domain.