As the 2020 Democratic presidential candidates argue for open borders, Republicans need to point out why illegal immigration is "morally wrong" -- or else they will be branded "evil" by the Left, according to Fox News contributor Jonathan Morris.

Morris said Democrats claim they have the moral high ground because they insist on open borders. But Morris, a theologian and ethicist, said that is not doing legal or illegal immigrants any favors.

"The idea that the Democrats are morally justified in saying, 'President Trump is evil. We are good. We're going to let everyone come in,' That is not the right way," Morris told "Fox & Friends" Tuesday morning. "We have to be tough, of course, and have a secure border."

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The former Catholic priest said the religious community is on the side of immigrants but: "I don't think the bishops in the United States would say open borders is the way to go."

He said the country needs a comprehensive and well-thought-out immigration plan. And being in favor of that does not mean you are against immigrants, he said.

"We have to do it in a way that’s good, not only for those here already but those coming over," he said. "The idea of living in the shadows for years and years...is not good for immigrants."

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Trump won the evangelical vote but Morris said Democrats are making a moral argument that the government, under the Trump administration, is "evil" because of raids carried out by Immigration and Customs Enforcement (ICE) and conditions at migrant border facilities.

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"The Democratic contenders are all saying open borders is the right thing to do for immigrants. It's actually the worst thing to do for immigrants," Morris concluded. "It's bad for our country that they're here illegally, it's bad for them."