You can use the adjective vehement to describe an extremely strong, powerful, or intense emotion or force. The teenager argued for a much later curfew in a vehement speech to her parents; her parents responded with an equally vehement “No way!”
Vehement is from Latin and was originally applied to intense natural phenomena: pain, heat, wind, etc. It is now more commonly used for intense emotions or beliefs. With the adverb form, people can be vehemently in favor of something, but the more common usage is for people to be vehemently opposed to something. Many people, for example, are vehemently opposed to politicians they didn't vote for, other people spoiling the endings of movies or books, or someone else taking the last piece of chocolate. The stress is on the first syllable (VEE-uh-ment).