The phrase "fervently disagree" is correct and can be used in written English.
It is used to express strong disagreement. For example: "I fervently disagree with the decision to close the library."
"But I fervently disagree with it, and I'm not going to stop explaining what I believe in".
In discussions with others, friends who work in technology and have fully adopted a digital life all seem to think they should simply be given away or thrown out; those on the other side of the street fervently disagree.
"Of course, I fervently disagree with Ed Balls about the role that he and the Labour government played in creating the economic crisis in the first place.
"The Avengers" star said there was nothing strange about the encounter — though many social media users (and anyone with working eyeballs) may fervently disagree.
If riots erupt, it is easy to get swept up in them and their anger, or to feel powerless to oppose even if you fervently disagree.
However, New York's police unions fervently disagree with the decision of the mayor and the police commissioner to settle the litigation.
In the same way, he fervently disagrees with some of the choices I've made in government," he continued.
One fervently disagreed with my entire keynote saying that it was morally wrong for women to be out of the home and that if the government did anything to advocate this, it would be a nightmare for Indonesian society, birth rates would go into free-fall and all hell would break loose.
O'Reilly fervently disagreed, saying "race hustlers" such as Lee don't want to have a conversation and that they "get voted into office by portraying their constituents as victims".
Its first principle is that we will never get the change we need without electoral reform, so that should be the point on which politicians who disagree fervently on other things can unite.
I disagree fervently with the people on our side of the aisle who have caved and who say, 'Well, I hope he succeeds.
