Pope Francis said on Saturday that he would be "honest" with the United States President Donald Trump about their sharp differences on things like immigration and climate change when they first meet in the Vatican later this month.

Trump is meeting with Pope on May 24

The Pope, however, told reporters on the plane on his return from Portugal that he would be without prejudice and that he will not judge Trump until he heard his views at their meeting that is scheduled to happen on May 24.

"Even if somebody thinks unlike we have to be very sincere," said Francis, adding that he is hoping to come to an "at least partially open door," and that he wishes that his conversation with Trump will contribute to world peace.

Last year, in answer to the question of Trump's candidate about immigration and his intentions to build a wall along the American border, Pope Francis said that a man with such opinion "is not a Christian."

Trump, who grew up in the Presbyterian family, replied that it was "shameful" that the pope questioned his faith.

Trump and Pope are also in great disagreement about climate issues Trump signed an executive order demolishing environmental laws from the time of former President Barack Obama. Francis made the environmental protection the main element of his papacy, strongly endorsing the view that global warming is a result of human doings.

Trump will visit Rome before his trip to Brussels for a NATO summit, and ahead of a visit to Sicily where he will attend the G7 summit of the world's most developed countries.

The future without wars

Pope Francis has turned attention to the suffering of people affected by wars and conflicts in the Middle East, as the United States supports the circle around the militant Islamic State in Iraq. "So many innocent lives are in difficult trials, whether they are Christians, Muslims or other minority groups such as the Jews, who suffer tragic violence and discrimination," the Pope said after his regular Sunday address to Vatican officials.

"I encourage different communities to follow the path of dialogue and friendship, to build the future of respect, security, and peace, far from any wars." This is an announcement that Pope said at a time when the battle for Mosul, the capital of the Islamic State in Iraq, is approaching its end after seven months of heavy fighting. In this area, Jihadists have been persecuting and torturing many of the quirks they consider unbelievers.