Advocacy group Christian Concern says the government's new definition of extremism could dangerously restrict Christian belief in the UK, particularly pro-life and gender-critical beliefs.
Communities Secretary Michael Gove has named several groups - some with Islamist connections and others on the far-right - that are to be investigated.
The new definition emerges amidst escalating community tensions over the Israel-Hamas war, and political disagreements about the control of pro-Palestinian protests in London.
The new definition will define extremism as "the promotion or advancement of an ideology based on violence, hatred or intolerance, that aims to:
1. negate or destroy the fundamental rights and freedoms of others; or
2. undermine, overturn or replace the UK's system of liberal parliamentary democracy and democratic rights; or
3. intentionally create a permissive environment for others to achieve the results in (1) or (2)."
However, Tim Dieppe, from the advocacy group Christian Concern, told Premier Christian News the freedom of the Christian faith could be at risk under the definition, particularly relating to pro-life, gender-critical and traditional Christian sexual ethics.
"I'm concerned here that if I'm opposed to, let's say, a right to abortion, is that seen as a fundamental rights and freedom of others? And does that make me an extremist? Because I could be deemed intolerant for that, as well. And so, would pro-life Christians be categorised as extremists?
"We already know that being anti-abortion is on the Prevent list of ideologies seen as potential signs of extremism. And then what about people who might say that there's a fundamental right to marriage? And would that include same-sex marriage? And if so, if I'm opposed to disagreeing with same-sex marriage, does that make me an extremist?"
A document from Prevent, the official scheme to stop radicalisation, listed anti-abortion alongside socialism, communism, and anti-fascism as ideologies that could potentially lead to terrorism.
Prevent's range of watchlist beliefs has already faced criticism from Neil Basu, a former police head of counter-terrorism, who described its list as "far too nebulous", lacking "qualification", and capable of "overwhelming the system".
From a Christian perspective, Dieppe told Premier Christian News, Christian Concern has already supported believers who've been referred to Prevent simply for expressing their Christian views.
"School chaplain Bernard Randall was referred to Prevent for preaching a sermon in which he told students, you're free to disagree with LGBT adults, you don't have to do that make up your own minds.
"And another school teacher, Svetlana Powell, was reported to prevent after discussion with a lesbian pupil in which she said God loves you. So I'm concerned that this definition could be used to classify Christians as extremists. And I think that would be very, very sad, and quite disturbing, in terms of our Christian freedoms, and how far we've come in our society from Christianity being absolutely at the centre of our morality and values as a nation."
So far, no groups with Christian links have been added to the government's list. Those added to the list, unlike terrorist groups, won't be criminalised. Simultaneously, the Counter-Extremism Centre of Excellence has been formed to gather intelligence and identify extremist factions.