Former Liberal MP Jim Karygiannis says Justin Trudeau's unexpected announcement requiring all incoming Liberal members of Parliament to vote pro-choice will "definitely" hurt the party and that the leader should rethink the policy.

Karygiannis, who is steadfastly anti-abortion, said on CBC News Network's Power & Politics on Tuesday that he doesn't think "pro-lifers" who used to be Liberal MPs would be welcomed back to Parliament and that current MPs with anti-abortion views are "having difficulty."

CBC host Evan Solomon asked Karygiannis if he believes Trudeau's move hurts the Liberal Party.

"Definitely," Karygiannis said. "Definitely it's going to hurt the party."

Karygiannis also criticized forcing parliamentarians to toe the party line, because there are Liberal members who hold "pro-life" views and citizens need their MPs "to think on their own."

"Here, we're not allowed to think. Members of Parliament that are saying — you know, candidates that are saying, 'I am pro-life' — they're not allowed to think," he said.

"I mean, you have to think whatever you're told," Karygiannis said, adding that his 25 years in Ottawa included "being a trained seal."

"I have to tell you, I feel liberated that I can voice my opinion," he said.

Karygiannis resigned from federal politics at the beginning of April in order to run for a seat on Toronto city council.

Woman's right to choose a 'charter right'

Liberal MP Carolyn Bennett, who appeared alongside Karygiannis on Power & Politics, said Trudeau was clear that people can hold their own views and choose to do what's right for themselves

"But when it comes to being a member of Parliament within the Liberal Party of Canada, Justin was very clear during the leadership that he would stick up for the woman's right to choose, which is a charter right."

Trudeau caused a furor on Parliament Hill earlier this month when he told reporters that all future Liberal candidates for the 2015 general election will have to support the party's pro-choice position when it comes to voting on bills. He said that rule wouldn't apply to existing MPs "to a certain extent."

In an email sent out to Liberal Party members on Victoria Day, Trudeau clarified that it doesn't prevent those who hold anti-abortion beliefs from joining the party.

"Canadians of all views are welcome within the Liberal Party of Canada," reads the email.

But some are not convinced.

Play by the leader's rules

Rev. Raymond de Souza, a Roman Catholic priest and editor in chief of Convivium Magazine, said Trudeau's email was "very strange."

"The letter that he released yesterday was a little bit more radical, because while the prime minister says he doesn't want to reopen this debate, Mr. Trudeau's position seems to be that there is no debate — at least not in the Liberal Party," he said on Power & Politics.

De Souza said it is "not a likely possibility" that Trudeau, who was raised Roman Catholic, would be excommunicated from the church.

At the same time, De Souza said that within Catholic and broader pro-life circles, "people would feel that the message from the Liberal Party here is that you're not welcome, you're not allowed to even have a voice in the caucus."

"There is the question of whether religious people, broadly speaking, are welcome in Canadian public life," he said.

"This will feed into a kind of a sense where you can play in the game, but only by the leader's rules and those rules aren't sympathetic to pro-lifers by any means."