Christian charities are reacting with horror at Trump's move to block all refugees from entering the US.

President Trump signed an executive order on Friday that banned all refugees fleeing war in Syria from coming to America and halted any entry for people from Iraq, Iran, Sudan, Somalia, Libya, and Yemen for 90 days.

The block prompted widespread condemnation from around the world with the European Parliament saying it would never choose isolation and inequality over openness and equality.

Iraq's parliament called for reciprocal action after it was one of seven countries named in the motion.

The United Nations also announced its opposition with UN human rights chief Zeid Ra'ad al-Hussein saying the ban was "mean-spirited and wastes resources needed for proper counter-terrorism".

The White House insisted the measure did not amount to a Muslim ban and insisted it would prioritise Christians fleeing persecution.

But Christians NGOs united in their defiance and lambasted Trump's plan as a rejection of Christian values.

A coalition of evangelical leaders including Leith Anderson, president of the National Association of Evangelicals (NAoE), Samual Rodriguez, president of the National Hispanic Christian Leadership Conference who prayed at Trump's inauguration, and Richard Stearns, president of World Vision US, wrote to Trump condemning the plans.

"The Bible teaches us that each person — including each refugee, regardless of their country of origin, religious background, or any other qualifier — is made in the Image of God, with inherent dignity and potential. Their lives matter to God, and they matter to us," a statement read.

"While the U.S. has in recent years received only a fraction of 1 percent of the world's refugees annually, we believe the refugee resettlement program provides a lifeline to these uniquely vulnerable individuals and a vital opportunity for our churches to live out the biblical commands to love our neighbors, to make disciples of all nations, and to practice hospitality."

Lobby group In Defense of Christians executive director Philippe Nassif called for a quick end to the ban and said it would be better to focus on creating safe zones for Christians in the Middle East.

"It is important to understand that Christians, Yazidis, and other religious minorities in Iraq and Syria have been victims of genocide perpetrated by ISIS, and formally recognized by the US Congress," he said.

"It is our belief at IDC that these genocide victims who seek asylum should be prioritized and given accommodation on the basis of this status. But that does not mean banning all refugees."

Christian Aid's head of advocacy, Tom Viita, said the President should read his Bible before implementing such policies.

"At the heart of the Christian faith is a clear command to 'love the stranger' and to stand with the vulnerable, whoever they may be," he said.

"To follow Christian teaching means to welcome people in need - whatever their faith - not prioritise people who happen to share one's own beliefs.

"A rejection of refugees, whatever their faith, is a rejection of Christian values. Trump would do well to read his bible before enacting discriminatory policies."

He accused Trump of "ripping up" post-World War Two treaties designed to protect people.

Persecution charity Open Doors' CEO Lisa Pearce said Trump was right to recognise the persecution faced by Christians but said he was wrong to target one religion for protection.

"Prioritising one religion over another only exacerbates the already severe worldwide trend of religious persecution," she told Christian Today.

"We encourage a need-based approach that treats all faiths equally and works toward the comprehensive strengthening of religious freedom around the world."