Pope Francis has written a Christmas letter to the Christians of the Middle East saying he is particularly concerned about the children, mothers, elderly, homeless and refugees as they face the prospect of a harsh winter.

He sent the letter to express his closeness to the Middle East Christians at a time of "afflictions and tribulations," the Vatican said on December 24.

This he said is due to "the continuing hostilities in the region, but especially because of the work of a newer and disturbing terrorist organization."

Though the Pope does not refer to the organization by name, Islamic State militants in recent months have forced hundreds of thousands of Christians, Yazidis and other minorities from their homes and villages in Iraq, notes the Vatican news service statement on the papal letter.

"I write to you just before Christmas, knowing that for many of you the music of your Christmas hymns will also be accompanied by tears and sighs," says Francis.

"Nonetheless, the birth of the Son of God in our human flesh is an indescribable mystery of consolation: 'For the grace of God has appeared for the salvation of all people [Tit 2:11].'"

The pontiff says he cannot remain silent in the face of persecution and conflict affecting other religious and ethnic groups.

He writes that he cannot remain silent in the face of persecution and conflict affecting other religious and ethnic groups. He is particularly concerned about the children, mothers, elderly, homeless and refugees as they face the prospect of a harsh winter.

Interreligious dialogue marked by openness, truth and love, he says, is the best antidote to religious fundamentalism, "a threat to followers of every religion."

Living in predominantly Muslim nations, the region's Christians can help their fellow Muslims present a "more authentic image of Islam," the Pope writes, "as so many of them desire."

Christians can reiterate that Islam is a religion of peace, compatible with respect for human rights and peaceful coexistence.

The tragic situation of the Christians, Yazidis and other minorities in Iraq, the Pope stresses, "demands that all religious leaders clearly...condemn these crimes unanimously and unambiguously" and "denounce the practice of invoking religion in order to justify them."

At the same time, says Francis as natives to the region, Christians "have the duty and the right to take full part in the life and progress of their nations."

They are called to be "artisans of peace, reconciliation and development, to promote dialogue," he says, to build bridges and cooperate with "all national and international authorities."

Pope Francis says Christians in the Middle East have "an enormous responsibility."

But, he assures them they are not alone – that he is here to encourage them and let them know how precious is their presence and witness. And, he hopes to one day come visit them in person, to comfort them.