What defines "an act of terrorism?"?

Terror, facing death. Seconds to live. When this happens to us, the blood drains from our face in fear, we turn sort of gray/green, Ash color. Severe Danger! End-time sign.

An act of terrorism is any act that terrorizes one or more people.

any act perpetrated by someone (regardless of faith, race, agenda, culture, nationality).. that strikes fear and horror in the hearts and souls of their victims.. that is terrorism

The word terrorist didn't exist when Christians invaded North America and murdered mass numbers of native men, women and children claiming their dead souls for their son of a god.

using violence and fear to push an ideology

Any act that is intended to instill fear, to disrupt, and cause terror among the biggest number possible.

It's not politically wise to use that word when you're talking about a Christian.

It is action to terrify another person, often due to the potentially fatal consequences of that action. Even kidnapping a person can rightly be called an act of terrorism because the kidnapped person is often abused sexually, psychologically, used as a slave and/or held as a ransom for money, otherwise they will be murdered. Mowing pedestrians down on the pavement by deliberately driving into them is an act of terrorism. Shooting indiscriminately into a crowd of people is an act of terrorism. Setting fire to living people is an act of terrorism. Throwing acid in the fact of a person is an act of terrorism.

Need I go on? Are you really serious in thinking Christian faith can equate with any of that?

Terrorism is an act of violence for political or superstitious reasons.

If you are looking to instill terror, then it is terrorism